diff --git a/.gitignore b/.gitignore
index eca79cd6..889367d5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -56,3 +56,4 @@ __pycache__
 .vscode/launch.json
 .vscode/settings.json
 .vscode/tasks.json
+/cmake-build-debug/
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 37f82dd4..149d19c4 100755
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -38,7 +38,9 @@ else()
     set(QT_VERSION_MAJOR 5)
 endif()
 find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Core Gui Widgets LinguistTools)
-message(STATUS "QT Major Version: " ${QT_VERSION_MAJOR})
+set(QT_VERSION ${Qt${QT_VERSION_MAJOR}Core_VERSION})
+
+message(STATUS "Qt Version: " ${QT_VERSION})
 
 add_definitions(${QT_DEFINITIONS})
 set(CMAKE_POSITION_INDEPENDENT_CODE ON)
diff --git a/qucs-activefilter/CMakeLists.txt b/qucs-activefilter/CMakeLists.txt
index 0a804cc5..5e8a4c20 100644
--- a/qucs-activefilter/CMakeLists.txt
+++ b/qucs-activefilter/CMakeLists.txt
@@ -52,15 +52,35 @@ else()
       )
 endif()
 
+set(QT_VERSION ${Qt${QT_VERSION_MAJOR}Core_VERSION})
 
-set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
-
-if (MSVC)
-  add_compile_options(/Zc:__cplusplus /permissive- /MP /Zc:preprocessor)
+if (${QT_VERSION} VERSION_LESS "6.7.0")
+    set(CMAKE_CXX_STANDARD 17)
 else()
-  # additional warnings
-  add_compile_options(-Wall -Wextra)
+    set(CMAKE_CXX_STANDARD 20)
+endif()
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+if (CMAKE_BUILD_TYPE STREQUAL "Debug")
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+        add_compile_definitions(_CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS)
+        add_compile_options(/permissive- /Zc:__cplusplus /Zc:preprocessor /MP /Od /vmg)
+        add_compile_options(/wd4244 /wd4267 /wd4312)
+    else()
+        add_compile_options(-Wall -Wextra -O0 -g)
+        if (CMAKE_CXX_COMPILER_ID MATCHES "^AppleClang$|^Clang$")
+            add_compile_options(-Wno-ignored-attributes)
+        endif()
+    endif()
+elseif(CMAKE_BUILD_TYPE STREQUAL "Release")
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+        add_compile_definitions(_CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS)
+        string(REGEX REPLACE "/W3" "/w" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+        add_compile_options(/permissive- /Zc:__cplusplus /Zc:preprocessor /MP /vmg)
+    else()
+        add_compile_options(-w)
+    endif()
 endif()
 
 ADD_DEFINITIONS(${QT_DEFINITIONS})
diff --git a/qucs-attenuator/CMakeLists.txt b/qucs-attenuator/CMakeLists.txt
index 8d450762..30d85580 100644
--- a/qucs-attenuator/CMakeLists.txt
+++ b/qucs-attenuator/CMakeLists.txt
@@ -39,16 +39,37 @@ include_directories(
       ${Qt${QT_VERSION_MAJOR}Widgets_INCLUDE_DIRS}
       )
 
+set(QT_VERSION ${Qt${QT_VERSION_MAJOR}Core_VERSION})
 
-set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
-
-if (MSVC)
-  add_compile_options(/Zc:__cplusplus /permissive- /MP /Zc:preprocessor)
+if (${QT_VERSION} VERSION_LESS "6.7.0")
+    set(CMAKE_CXX_STANDARD 17)
 else()
-  # additional warnings
-  add_compile_options(-Wall -Wextra)
+    set(CMAKE_CXX_STANDARD 20)
 endif()
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+if (CMAKE_BUILD_TYPE STREQUAL "Debug")
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+        add_compile_definitions(_CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS)
+        add_compile_options(/permissive- /Zc:__cplusplus /Zc:preprocessor /MP /Od /vmg)
+        add_compile_options(/wd4244 /wd4267 /wd4312)
+    else()
+        add_compile_options(-Wall -Wextra -O0 -g)
+        if (CMAKE_CXX_COMPILER_ID MATCHES "^AppleClang$|^Clang$")
+            add_compile_options(-Wno-ignored-attributes)
+        endif()
+    endif()
+elseif(CMAKE_BUILD_TYPE STREQUAL "Release")
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+        add_compile_definitions(_CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS)
+        string(REGEX REPLACE "/W3" "/w" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+        add_compile_options(/permissive- /Zc:__cplusplus /Zc:preprocessor /MP /vmg)
+    else()
+        add_compile_options(-w)
+    endif()
+endif()
+
 ADD_DEFINITIONS(${QT_DEFINITIONS})
 
 #ADD_SUBDIRECTORY( bitmaps ) -> added as resources
diff --git a/qucs-filter/CMakeLists.txt b/qucs-filter/CMakeLists.txt
index 07527ded..1d70c195 100644
--- a/qucs-filter/CMakeLists.txt
+++ b/qucs-filter/CMakeLists.txt
@@ -42,14 +42,35 @@ include_directories(
       )
 
 
-set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(QT_VERSION ${Qt${QT_VERSION_MAJOR}Core_VERSION})
 
-if (MSVC)
-  add_compile_options(/Zc:__cplusplus /permissive- /MP /Zc:preprocessor)
+if (${QT_VERSION} VERSION_LESS "6.7.0")
+    set(CMAKE_CXX_STANDARD 17)
 else()
-  # additional warnings
-  add_compile_options(-Wall -Wextra)
+    set(CMAKE_CXX_STANDARD 20)
+endif()
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+if (CMAKE_BUILD_TYPE STREQUAL "Debug")
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+        add_compile_definitions(_CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS)
+        add_compile_options(/permissive- /Zc:__cplusplus /Zc:preprocessor /MP /Od /vmg)
+        add_compile_options(/wd4244 /wd4267 /wd4312)
+    else()
+        add_compile_options(-Wall -Wextra -O0 -g)
+        if (CMAKE_CXX_COMPILER_ID MATCHES "^AppleClang$|^Clang$")
+            add_compile_options(-Wno-ignored-attributes)
+        endif()
+    endif()
+elseif(CMAKE_BUILD_TYPE STREQUAL "Release")
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+        add_compile_definitions(_CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS)
+        string(REGEX REPLACE "/W3" "/w" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+        add_compile_options(/permissive- /Zc:__cplusplus /Zc:preprocessor /MP /vmg)
+    else()
+        add_compile_options(-w)
+    endif()
 endif()
 
 ADD_DEFINITIONS(${QT_DEFINITIONS})
diff --git a/qucs-powercombining/CMakeLists.txt b/qucs-powercombining/CMakeLists.txt
index 7bc4fe48..e7e5a3c2 100644
--- a/qucs-powercombining/CMakeLists.txt
+++ b/qucs-powercombining/CMakeLists.txt
@@ -51,15 +51,35 @@ else()
         )
 endif()
 
+set(QT_VERSION ${Qt${QT_VERSION_MAJOR}Core_VERSION})
 
-set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
-
-if (MSVC)
- add_compile_options(/Zc:__cplusplus /permissive- /MP /Zc:preprocessor)
+if (${QT_VERSION} VERSION_LESS "6.7.0")
+    set(CMAKE_CXX_STANDARD 17)
 else()
-  # additional warnings
-  add_compile_options(-Wall -Wextra)
+    set(CMAKE_CXX_STANDARD 20)
+endif()
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+if (CMAKE_BUILD_TYPE STREQUAL "Debug")
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+        add_compile_definitions(_CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS)
+        add_compile_options(/permissive- /Zc:__cplusplus /Zc:preprocessor /MP /Od /vmg)
+        add_compile_options(/wd4244 /wd4267 /wd4312)
+    else()
+        add_compile_options(-Wall -Wextra -O0 -g)
+        if (CMAKE_CXX_COMPILER_ID MATCHES "^AppleClang$|^Clang$")
+            add_compile_options(-Wno-ignored-attributes)
+        endif()
+    endif()
+elseif(CMAKE_BUILD_TYPE STREQUAL "Release")
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+        add_compile_definitions(_CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS)
+        string(REGEX REPLACE "/W3" "/w" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+        add_compile_options(/permissive- /Zc:__cplusplus /Zc:preprocessor /MP /vmg)
+    else()
+        add_compile_options(-w)
+    endif()
 endif()
 
 ADD_DEFINITIONS(${QT_DEFINITIONS})
diff --git a/qucs-powercombining/qucspowercombiningtool.cpp b/qucs-powercombining/qucspowercombiningtool.cpp
index 17a44051..67c1d8f5 100644
--- a/qucs-powercombining/qucspowercombiningtool.cpp
+++ b/qucs-powercombining/qucspowercombiningtool.cpp
@@ -794,7 +794,7 @@ QString QucsPowerCombiningTool::calcChebyLines(double RL, double Z0, double gamm
     //double sec_theta_m = cosh((1/(1.*N))*acosh(fabs(log(RL/Z0)/(2*gamma))) );
     (fabs(log(RL/Z0)/(2*gamma)) < 1) ? sec_theta_m = 0 : sec_theta_m = cosh((1/(1.*N))*acosh(fabs(log(RL/Z0)/(2*gamma))) );
 
-    double w[7]; // for msvc predefined size.
+    std::vector<double> w(N,0.0);
 
     switch(N)//The weights are calculated by equating the reflection coeffient formula to the N-th Chebyshev polinomial
     {
diff --git a/qucs-transcalc/CMakeLists.txt b/qucs-transcalc/CMakeLists.txt
index 21b62d1b..5f1f2edf 100644
--- a/qucs-transcalc/CMakeLists.txt
+++ b/qucs-transcalc/CMakeLists.txt
@@ -41,14 +41,35 @@ include_directories(
       )
 
 
-set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(QT_VERSION ${Qt${QT_VERSION_MAJOR}Core_VERSION})
 
-if (MSVC)
-  add_compile_options(/Zc:__cplusplus /permissive- /MP /Zc:preprocessor)
+if (${QT_VERSION} VERSION_LESS "6.7.0")
+    set(CMAKE_CXX_STANDARD 17)
 else()
-  # additional warnings
-  add_compile_options(-Wall -Wextra)
+    set(CMAKE_CXX_STANDARD 20)
+endif()
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+if (CMAKE_BUILD_TYPE STREQUAL "Debug")
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+        add_compile_definitions(_CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS)
+        add_compile_options(/permissive- /Zc:__cplusplus /Zc:preprocessor /MP /Od /vmg)
+        add_compile_options(/wd4244 /wd4267 /wd4312)
+    else()
+        add_compile_options(-Wall -Wextra -O0 -g)
+        if (CMAKE_CXX_COMPILER_ID MATCHES "^AppleClang$|^Clang$")
+            add_compile_options(-Wno-ignored-attributes)
+        endif()
+    endif()
+elseif(CMAKE_BUILD_TYPE STREQUAL "Release")
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+        add_compile_definitions(_CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS)
+        string(REGEX REPLACE "/W3" "/w" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+        add_compile_options(/permissive- /Zc:__cplusplus /Zc:preprocessor /MP /vmg)
+    else()
+        add_compile_options(-w)
+    endif()
 endif()
 
 ADD_DEFINITIONS(${QT_DEFINITIONS})
diff --git a/qucs/CMakeLists.txt b/qucs/CMakeLists.txt
index cbae80c3..57e43b24 100755
--- a/qucs/CMakeLists.txt
+++ b/qucs/CMakeLists.txt
@@ -81,18 +81,40 @@ CONFIGURE_FILE (
 INCLUDE_DIRECTORIES("${PROJECT_BINARY_DIR}")
 
 IF(QT_VERSION_MAJOR EQUAL 6)
-set(CMAKE_AUTOUIC ON)
-set(CMAKE_AUTOMOC ON)
-set(CMAKE_AUTORCC ON)
+    set(CMAKE_AUTOUIC ON)
+    set(CMAKE_AUTOMOC ON)
+    set(CMAKE_AUTORCC ON)
 ENDIF()
-set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
-if (MSVC)
-    add_compile_options(/Zc:__cplusplus /permissive- /MP /Zc:preprocessor)
+set(QT_VERSION ${Qt${QT_VERSION_MAJOR}Core_VERSION})
+
+if (${QT_VERSION} VERSION_LESS "6.7.0")
+    set(CMAKE_CXX_STANDARD 17)
 else()
-    # additional warnings
-    add_compile_options(-Wall -Wextra)
+    set(CMAKE_CXX_STANDARD 20)
+endif()
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+if (CMAKE_BUILD_TYPE STREQUAL "Debug")
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+        add_compile_definitions(_CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS)
+        add_compile_options(/permissive- /Zc:__cplusplus /Zc:preprocessor /MP /Od /vmg)
+        add_compile_options(/wd4244 /wd4267 /wd4312)
+    else()
+        add_compile_options(-Wall -Wextra -O0 -g)
+        if (CMAKE_CXX_COMPILER_ID MATCHES "^AppleClang$|^Clang$")
+            add_compile_options(-Wno-ignored-attributes)
+        endif()
+    endif()
+elseif(CMAKE_BUILD_TYPE STREQUAL "Release")
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+        add_compile_definitions(_CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS)
+        string(REGEX REPLACE "/W3" "/w" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+        add_compile_options(/permissive- /Zc:__cplusplus /Zc:preprocessor /MP /vmg)
+    else()
+        add_compile_options(-w)
+    endif()
 endif()
 
 INCLUDE_DIRECTORIES(
@@ -209,25 +231,25 @@ endif()
 # configure Apple bundle information
 #
 IF(APPLE)
-  # set information on Info.plist file
-	SET(MACOSX_BUNDLE_INFO_STRING "${PROJECT_NAME} ${PROJECT_VERSION}")
-  SET(MACOSX_BUNDLE_BUNDLE_VERSION "${PROJECT_NAME} ${PROJECT_VERSION}")
-  SET(MACOSX_BUNDLE_LONG_VERSION_STRING "${PROJECT_NAME} ${PROJECT_VERSION}")
-  SET(MACOSX_BUNDLE_SHORT_VERSION_STRING "${PROJECT_VERSION}")
-  SET(MACOSX_BUNDLE_COPYRIGHT "${PROJECT_COPYRIGHT_YEAR} ${PROJECT_VENDOR}")
-  SET(MACOSX_BUNDLE_GUI_IDENTIFIER "${PROJECT_DOMAIN_SECOND}.${PROJECT_DOMAIN_FIRST}")
-  SET(MACOSX_BUNDLE_BUNDLE_NAME "${PROJECT_NAME}")
-  SET(MACOSX_BUNDLE_ICON_FILE qucs.icns)
-
-  # set where in the bundle to put the icns file
-  SET_SOURCE_FILES_PROPERTIES(${CMAKE_CURRENT_SOURCE_DIR}/bitmaps/qucs.icns PROPERTIES MACOSX_PACKAGE_LOCATION Resources)
-  # include the icns file in the target
-  SET(QUCS_SRCS ${QUCS_SRCS} ${CMAKE_CURRENT_SOURCE_DIR}/bitmaps/qucs.icns)
-
-  # This tells cmake where to place the translations inside the bundle
-  #SET_SOURCE_FILES_PROPERTIES( ${LANG_SRCS} PROPERTIES MACOSX_PACKAGE_LOCATION Resources/lang )
-  # include the translation files in the target
-  #SET(RESOURCES_SRCS ${RESOURCES_SRCS} ${LANG_SRCS})
+    # set information on Info.plist file
+    SET(MACOSX_BUNDLE_INFO_STRING "${PROJECT_NAME} ${PROJECT_VERSION}")
+    SET(MACOSX_BUNDLE_BUNDLE_VERSION "${PROJECT_NAME} ${PROJECT_VERSION}")
+    SET(MACOSX_BUNDLE_LONG_VERSION_STRING "${PROJECT_NAME} ${PROJECT_VERSION}")
+    SET(MACOSX_BUNDLE_SHORT_VERSION_STRING "${PROJECT_VERSION}")
+    SET(MACOSX_BUNDLE_COPYRIGHT "${PROJECT_COPYRIGHT_YEAR} ${PROJECT_VENDOR}")
+    SET(MACOSX_BUNDLE_GUI_IDENTIFIER "${PROJECT_DOMAIN_SECOND}.${PROJECT_DOMAIN_FIRST}")
+    SET(MACOSX_BUNDLE_BUNDLE_NAME "${PROJECT_NAME}")
+    SET(MACOSX_BUNDLE_ICON_FILE qucs.icns)
+
+    # set where in the bundle to put the icns file
+    SET_SOURCE_FILES_PROPERTIES(${CMAKE_CURRENT_SOURCE_DIR}/bitmaps/qucs.icns PROPERTIES MACOSX_PACKAGE_LOCATION Resources)
+    # include the icns file in the target
+    SET(QUCS_SRCS ${QUCS_SRCS} ${CMAKE_CURRENT_SOURCE_DIR}/bitmaps/qucs.icns)
+
+    # This tells cmake where to place the translations inside the bundle
+    #SET_SOURCE_FILES_PROPERTIES( ${LANG_SRCS} PROPERTIES MACOSX_PACKAGE_LOCATION Resources/lang )
+    # include the translation files in the target
+    #SET(RESOURCES_SRCS ${RESOURCES_SRCS} ${LANG_SRCS})
 ENDIF(APPLE)
 
 
diff --git a/qucs/components/DLS_1ton.cpp b/qucs/components/DLS_1ton.cpp
index b3f05ff6..3ca0e922 100644
--- a/qucs/components/DLS_1ton.cpp
+++ b/qucs/components/DLS_1ton.cpp
@@ -30,7 +30,7 @@ DLS_1ton::DLS_1ton()
 Component * DLS_1ton::newOne()
 {
   DLS_1ton * p = new DLS_1ton();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/DLS_nto1.cpp b/qucs/components/DLS_nto1.cpp
index 98b7a5c2..044c85a6 100644
--- a/qucs/components/DLS_nto1.cpp
+++ b/qucs/components/DLS_nto1.cpp
@@ -31,7 +31,7 @@ DLS_nto1::DLS_nto1()
 Component * DLS_nto1::newOne()
 {
   DLS_nto1 * p = new DLS_nto1();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/MESFET.cpp b/qucs/components/MESFET.cpp
index 7c2e3c5f..8a601332 100644
--- a/qucs/components/MESFET.cpp
+++ b/qucs/components/MESFET.cpp
@@ -162,7 +162,7 @@ MESFET::MESFET()
 Component * MESFET::newOne()
 {
   MESFET * p = new MESFET();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/ac_sim.cpp b/qucs/components/ac_sim.cpp
index a9486ae6..a3a8b8df 100644
--- a/qucs/components/ac_sim.cpp
+++ b/qucs/components/ac_sim.cpp
@@ -64,21 +64,18 @@ Element* AC_Sim::info(QString& Name, char* &BitmapFile, bool getNewOne)
 
 void AC_Sim::recreate(Schematic*)
 {
-  Property *pp = Props.first();
-  if((pp->Value == "list") || (pp->Value == "const")) {
+  if((Props.at(0)->Value == "list") || (Props.at(0)->Value == "const")) {
     // Call them "Symbol" to omit them in the netlist.
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    Props.next()->Name = "Values";
+    Props.at(1)->Name = "Symbol";
+    Props.at(1)->display = false;
+    Props.at(2)->Name = "Symbol";
+    Props.at(2)->display = false;
+    Props.at(3)->Name = "Values";
   }
   else {
-    Props.next()->Name = "Start";
-    Props.next()->Name = "Stop";
-    Props.next()->Name = "Points";
+    Props.at(1)->Name = "Start";
+    Props.at(2)->Name = "Stop";
+    Props.at(3)->Name = "Points";
   }
 }
 
diff --git a/qucs/components/andor4x2.cpp b/qucs/components/andor4x2.cpp
index 5fba981e..e2f72d61 100644
--- a/qucs/components/andor4x2.cpp
+++ b/qucs/components/andor4x2.cpp
@@ -40,7 +40,7 @@ andor4x2::andor4x2()
 Component * andor4x2::newOne()
 {
   andor4x2 * p = new andor4x2();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/andor4x3.cpp b/qucs/components/andor4x3.cpp
index 05e6eb0d..e8d3a8e9 100644
--- a/qucs/components/andor4x3.cpp
+++ b/qucs/components/andor4x3.cpp
@@ -40,7 +40,7 @@ andor4x3::andor4x3()
 Component * andor4x3::newOne()
 {
   andor4x3 * p = new andor4x3();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/andor4x4.cpp b/qucs/components/andor4x4.cpp
index 74636987..4b555179 100644
--- a/qucs/components/andor4x4.cpp
+++ b/qucs/components/andor4x4.cpp
@@ -41,7 +41,7 @@ andor4x4::andor4x4()
 Component * andor4x4::newOne()
 {
   andor4x4 * p = new andor4x4();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/binarytogrey4bit.cpp b/qucs/components/binarytogrey4bit.cpp
index 556bd266..54ae6d1c 100644
--- a/qucs/components/binarytogrey4bit.cpp
+++ b/qucs/components/binarytogrey4bit.cpp
@@ -41,7 +41,7 @@ binarytogrey4bit::binarytogrey4bit()
 Component * binarytogrey4bit::newOne()
 {
   binarytogrey4bit * p = new binarytogrey4bit();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/bjt.cpp b/qucs/components/bjt.cpp
index d178b2ed..79550791 100644
--- a/qucs/components/bjt.cpp
+++ b/qucs/components/bjt.cpp
@@ -37,7 +37,7 @@ BJT::BJT()
 Component* BJT::newOne()
 {
   BJT* p = new BJT();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0);
   return p;
 }
@@ -85,7 +85,7 @@ Element* BJT::info_pnp(QString& Name, char* &BitmapFile, bool getNewOne)
 
   if(getNewOne) {
     BJT* p = new BJT();
-    p->Props.getFirst()->Value = "pnp";
+    p->Props.at(0)->Value = "pnp";
     p->recreate(0);
     return p;
   }
@@ -102,7 +102,7 @@ void BJT::createSymbol()
   Lines.append(new qucs::Line(-10,  5,  0, 15,QPen(Qt::darkBlue,2)));
   Lines.append(new qucs::Line(  0, 15,  0, 30,QPen(Qt::darkBlue,2)));
 
-  if(Props.getFirst()->Value == "npn") {
+  if(Props.front()->Value == "npn") {
     Lines.append(new qucs::Line( -6, 15,  0, 15,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line(  0,  9,  0, 15,QPen(Qt::darkBlue,2)));
   }
@@ -130,7 +130,7 @@ QString BJT::netlist()
   s += " "+Ports.at(1)->Connection->Name;  // connect substrate to collector
 
   // output all properties
-  for(Property *p2 = Props.first(); p2 != nullptr; p2 = Props.next())
+  for(const auto& p2 : Props)
     s += " "+p2->Name+"=\""+p2->Value+"\"";
 
   return s + '\n';
diff --git a/qucs/components/bjtsub.cpp b/qucs/components/bjtsub.cpp
index 0ff64622..a642cf2d 100644
--- a/qucs/components/bjtsub.cpp
+++ b/qucs/components/bjtsub.cpp
@@ -138,7 +138,7 @@ BJTsub::BJTsub()
 Component* BJTsub::newOne()
 {
   BJTsub* p = new BJTsub();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0);
   return p;
 }
@@ -161,7 +161,7 @@ Element* BJTsub::info_pnp(QString& Name, char* &BitmapFile, bool getNewOne)
 
   if(getNewOne) {
     BJTsub* p = new BJTsub();
-    p->Props.getFirst()->Value = "pnp";
+    p->Props.front()->Value = "pnp";
     p->recreate(0);
     return p;
   }
@@ -181,7 +181,7 @@ void BJTsub::createSymbol()
   Lines.append(new qucs::Line(  9,  0, 30,  0,QPen(Qt::darkBlue,2)));
   Lines.append(new qucs::Line(  9, -7,  9,  7,QPen(Qt::darkBlue,3)));
 
-  if(Props.getFirst()->Value == "npn") {
+  if(Props.front()->Value == "npn") {
     Lines.append(new qucs::Line( -6, 15,  0, 15,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line(  0,  9,  0, 15,QPen(Qt::darkBlue,2)));
   }
diff --git a/qucs/components/capacitor.cpp b/qucs/components/capacitor.cpp
index 6358987b..6a4f3d29 100644
--- a/qucs/components/capacitor.cpp
+++ b/qucs/components/capacitor.cpp
@@ -87,7 +87,7 @@ QString Capacitor::va_code()
 
 void Capacitor::createSymbol()
 {
-  if(Props.getLast()->Value.at(0) == 'n') {
+  if(Props.back()->Value.at(0) == 'n') {
     Lines.append(new qucs::Line( -4,-11, -4, 11,QPen(Qt::darkBlue,4)));
     Lines.append(new qucs::Line(  4,-11,  4, 11,QPen(Qt::darkBlue,4)));
   }
diff --git a/qucs/components/comp_1bit.cpp b/qucs/components/comp_1bit.cpp
index 6e48455e..73aabad0 100644
--- a/qucs/components/comp_1bit.cpp
+++ b/qucs/components/comp_1bit.cpp
@@ -41,7 +41,7 @@ comp_1bit::comp_1bit()
 Component * comp_1bit::newOne()
 {
   comp_1bit * p = new comp_1bit();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/comp_2bit.cpp b/qucs/components/comp_2bit.cpp
index da9f1e0a..9e45e28c 100644
--- a/qucs/components/comp_2bit.cpp
+++ b/qucs/components/comp_2bit.cpp
@@ -40,7 +40,7 @@ comp_2bit::comp_2bit()
 Component * comp_2bit::newOne()
 {
   comp_2bit * p = new comp_2bit();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/comp_4bit.cpp b/qucs/components/comp_4bit.cpp
index a29bf290..f208fddb 100644
--- a/qucs/components/comp_4bit.cpp
+++ b/qucs/components/comp_4bit.cpp
@@ -40,7 +40,7 @@ comp_4bit::comp_4bit()
 Component * comp_4bit::newOne()
 {
   comp_4bit * p = new comp_4bit();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/component.cpp b/qucs/components/component.cpp
index 5a3e01ce..263ea4f4 100644
--- a/qucs/components/component.cpp
+++ b/qucs/components/component.cpp
@@ -64,7 +64,6 @@ Component::Component() {
     tx = 0;
     ty = 0;
 
-    Props.setAutoDelete(true);
 
     containingSchematic = NULL;
 }
@@ -549,7 +548,7 @@ void Component::rotate() {
         dx = metrics.boundingRect(Name).width();
         dy = metrics.lineSpacing();
     }
-    for (Property *pp = Props.first(); pp != 0; pp = Props.next())
+    for (Property *pp : Props)
         if (pp->display) {
             // get width of text
             tmp = metrics.boundingRect(pp->Name + "=" + pp->Value).width();
@@ -631,7 +630,7 @@ void Component::mirrorX() {
     int dy = 0;
     if (showName)
         dy = metrics.lineSpacing();   // for "Name"
-    for (Property *pp = Props.first(); pp != nullptr; pp = Props.next())
+    for (Property *pp : Props)
         if (pp->display) dy += metrics.lineSpacing();
     if ((tx > x1) && (tx < x2)) ty = -ty - dy;     // mirror text position
     else ty = y1 + ty + y2;
@@ -699,7 +698,7 @@ void Component::mirrorY() {
     int dx = 0;
     if (showName)
         dx = metrics.boundingRect(Name).width();
-    for (Property *pp = Props.first(); pp != 0; pp = Props.next())
+    for (Property *pp : Props)
         if (pp->display) {
             // get width of text
             tmp = metrics.boundingRect(pp->Name + "=" + pp->Value).width();
@@ -723,7 +722,7 @@ QString Component::netlist() {
         s += " " + p1->Connection->Name;   // node names
 
     // output all properties
-    for (Property *p2 = Props.first(); p2 != nullptr; p2 = Props.next())
+    for (Property *p2 : Props)
         if (p2->Name != "Symbol")
             s += " " + p2->Name + "=\"" + p2->Value + "\"";
 
@@ -941,7 +940,7 @@ QString Component::save() {
     s += " " + QString::number(rotated);
 
     // write all properties
-    for (Property *p1 = Props.first(); p1 != 0; p1 = Props.next()) {
+    for (Property *p1 : Props) {
         QString val = p1->Value; // enable newline in properties
         val.replace("\n", "\\n");
         val.replace("\"", "''");
@@ -1013,7 +1012,7 @@ bool Component::load(const QString &_s) {
     tx = ttx;
     ty = tty; // restore text position (was changed by rotate/mirror)
 
-    unsigned int z = 0, counts = s.count('"');
+    unsigned int counts = s.count('"');
     if (Model == "Sub")
         tmp = 2;   // first property (File) already exists
     else if (Model == "Lib")
@@ -1028,12 +1027,14 @@ bool Component::load(const QString &_s) {
         tmp = 5; // number of properties for the default MUTX (2 inductors)
     else tmp = counts + 1;    // "+1" because "counts" could be zero
 
-    for (; tmp <= (int) counts / 2; tmp++)
-        Props.append(new Property("p", "", true, " "));
+    for (; tmp <= (int) counts / 2; tmp++){
+      Props.append(new Property("p", "", true, " "));
+    }
+
 
     // load all properties
-    Property *p1;
-    for (p1 = Props.first(); p1 != 0; p1 = Props.next()) {
+    unsigned int z = 0;
+    for (auto p1 = Props.begin(); p1 != Props.end(); ++p1) {
         z++;
         n = s.section('"', z, z);    // property value
         n.replace("\\n", "\n");
@@ -1043,76 +1044,87 @@ bool Component::load(const QString &_s) {
 
         // not all properties have to be mentioned (backward compatible)
         if (z > counts) {
-            if (p1->Description.isEmpty())
-                Props.remove();    // remove if allocated in vain
+            if ((*p1)->Description.isEmpty()){
+              Props.erase(p1++);   // remove if allocated in vain
+            }
 
             if (Model == "Diode") {
                 if (counts < 56) {  // backward compatible
                     counts >>= 1;
-                    p1 = Props.at(counts - 1);
-                    for (; p1 != 0; p1 = Props.current()) {
-                        if (counts-- < 19)
-                            break;
-
-                        n = Props.prev()->Value;
-                        p1->Value = n;
+                    p1 = Props.begin();
+                    std::advance(p1,std::min<int>(counts-1, std::distance(p1, Props.end())));
+                    for (; p1 != Props.begin();) {
+                        if (counts-- < 19){break;}
+
+                        auto p1prev = p1;
+                        --p1prev;
+                        n = (*p1prev)->Value;
+                        (*p1)->Value = n;
+                        --p1;
                     }
 
-                    p1 = Props.at(17);
-                    p1->Value = Props.at(11)->Value;
-                    Props.current()->Value = "0";
+                    Props.at(17)->Value = Props.at(11)->Value;
+                    (*p1)->Value = "0";
                 }
             } else if (Model == "AND" || Model == "NAND" || Model == "NOR" ||
                        Model == "OR" || Model == "XNOR" || Model == "XOR") {
                 if (counts < 10) {   // backward compatible
                     counts >>= 1;
-                    p1 = Props.at(counts);
-                    for (; p1 != 0; p1 = Props.current()) {
-                        if (counts-- < 4)
-                            break;
-                        n = Props.prev()->Value;
-                        p1->Value = n;
+                    p1 = Props.begin();
+                    std::advance(p1,std::min<int>(counts, std::distance(p1, Props.end())));
+                    for (; p1 != Props.begin();) {
+                      if (counts-- < 4){break;}
+                        auto p1prev = p1;
+                        --p1prev;
+                        n = (*p1prev)->Value;
+                        (*p1)->Value = n;
+                        --p1;
                     }
-                    Props.current()->Value = "10";
+                    (*p1)->Value = "10";
                 }
             } else if (Model == "Buf" || Model == "Inv") {
                 if (counts < 8) {   // backward compatible
                     counts >>= 1;
-                    p1 = Props.at(counts);
-                    for (; p1 != 0; p1 = Props.current()) {
-                        if (counts-- < 3)
-                            break;
-                        n = Props.prev()->Value;
-                        p1->Value = n;
+                    p1 = Props.begin();
+                    std::advance(p1,std::min<int>(counts, std::distance(p1, Props.end())));
+                    for(; p1 != Props.begin(); ) {
+                        if (counts-- < 3) {break;}
+
+                        auto p1prev = p1;
+                        --p1prev;
+                        n = (*p1prev)->Value;
+                        (*p1)->Value = n;
+                        --p1;
                     }
-                    Props.current()->Value = "10";
-                }
+                    (*p1)->Value = "10";
+                  }
             }
-
             return true;
         }
 
         // for equations
-        if (Model != "EDD" && Model != "RFEDD" && Model != "RFEDD2P")
-            if (p1->Description.isEmpty() || p1->Description == "Expression") {  // unknown number of properties ?
-                p1->Name = n.section('=', 0, 0);
-                n = n.section('=', 1);
-                // allocate memory for a new property (e.g. for equations)
-                if (Props.count() < (counts >> 1)) {
-                    Props.insert(z >> 1, new Property("y", "1", true));
-                    Props.prev();
-                }
+        if (Model != "EDD" && Model != "RFEDD" && Model != "RFEDD2P"){
+          if ((*p1)->Description.isEmpty() || (*p1)->Description == "Expression") {  // unknown number of properties ?
+            (*p1)->Name = n.section('=', 0, 0);
+            n = n.section('=', 1);
+            // allocate memory for a new property (e.g. for equations)
+            if (Props.size() < (counts >> 1)) {
+              int index = std::distance(Props.begin(), p1);
+              Props.insert(index + 1, new Property("y", "1", true));
+              p1 = Props.begin() + index;
             }
-        if (z == 6)
-            if (counts == 6)     // backward compatible
-                if (Model == "R") {
-                    Props.getLast()->Value = n;
-                    return true;
-                }
-        p1->Value = n;
+          }
+        }
+
+
+        if (z == 6 && counts == 6 && Model == "R"){ // backward compatible
+            Props.back()->Value = n;
+            return true;
+        }
+        (*p1)->Value = n;
 
         n = s.section('"', z, z);    // display
-        p1->display = (n.at(1) == '1');
+        (*p1)->display = (n.at(1) == '1');
     }
 
     return true;
@@ -1181,30 +1193,31 @@ int Component::analyseLine(const QString &Row, int numProps) {
         if (Name.isEmpty()) Name = "SUB";
 
         i1 = 1;
-        Property *pp = Props.at(numProps - 1);
+        auto pp = Props.begin();
+        std::advance(pp,std::min<int>( (numProps-1), std::distance(pp, Props.end())));
         for (;;) {
             s = Row.section('"', i1, i1);
             if (s.isEmpty()) break;
 
-            pp = Props.next();
-            if (pp == 0) {
-                pp = new Property();
-                Props.append(pp);
-
-                pp->display = (s.at(0) == '1');
-                pp->Value = s.section('=', 2, 2);
+            pp++;
+            if (pp == Props.end()) {
+                Props.append(new Property());
+                pp = --Props.end();
+                (*pp)->display = (s.at(0) == '1');
+                (*pp)->Value = s.section('=', 2, 2);
             }
 
-            pp->Name = s.section('=', 1, 1);
-            pp->Description = s.section('=', 3, 3);
-            if (pp->Description.isEmpty())
-                pp->Description = " ";
+            (*pp)->Name = s.section('=', 1, 1);
+            (*pp)->Description = s.section('=', 3, 3);
+            if ((*pp)->Description.isEmpty())
+                (*pp)->Description = " ";
 
             i1 += 2;
         }
 
-        while (pp != Props.last())
-            Props.remove();
+        if(pp != Props.end()-1){
+            Props.erase(pp, Props.end());
+        }
         return 0;   // do not count IDs
     } else if (s == "Arrow") {
         if (!getIntegers(Row, &i1, &i2, &i3, &i4, &i5, &i6)) return -1;
@@ -1401,12 +1414,14 @@ bool Component::getBrush(const QString &s, QBrush &Brush, int i) {
 }
 
 // ---------------------------------------------------------------------
-Property *Component::getProperty(const QString &name) {
-    for (Property *pp = Props.first(); pp != 0; pp = Props.next())
-        if (pp->Name == name) {
-            return pp;
-        }
-    return NULL;
+Property *Component::getProperty(const QString &name) {      
+    for(auto pp = Props.begin(); pp != Props.end(); ++pp) {
+      if((*pp)->Name == name) {
+        return *pp;
+      }
+    }
+
+    return nullptr;
 }
 
 // ---------------------------------------------------------------------
@@ -1511,12 +1526,9 @@ QString GateComponent::netlist() {
         s += " " + pp->Connection->Name;   // node names
 
     // output all properties
-    Property *p = Props.at(1);
-    s += " " + p->Name + "=\"" + p->Value + "\"";
-    p = Props.next();
-    s += " " + p->Name + "=\"" + p->Value + "\"";
-    p = Props.next();
-    s += " " + p->Name + "=\"" + p->Value + "\"\n";
+    s += " " + Props.at(1)->Name + "=\"" + Props.at(1)->Value + "\"";
+    s += " " + Props.at(2)->Name + "=\"" + Props.at(2)->Value + "\"";
+    s += " " + Props.at(3)->Name + "=\"" + Props.at(3)->Value + "\"\n";
     return s;
 }
 
@@ -1653,10 +1665,10 @@ QString GateComponent::verilogCode(int NumPorts) {
 
 // -------------------------------------------------------
 void GateComponent::createSymbol() {
-    int Num = Props.getFirst()->Value.toInt();
+    int Num = Props.front()->Value.toInt();
     if (Num < 2) Num = 2;
     else if (Num > 8) Num = 8;
-    Props.getFirst()->Value = QString::number(Num);
+    Props.front()->Value = QString::number(Num);
 
     int xl, xr, y = 10 * Num, z;
     x1 = -30;
@@ -1670,7 +1682,7 @@ void GateComponent::createSymbol() {
     z = 0;
     if (Model.at(0) == 'N') z = 1;
 
-    if (Props.getLast()->Value.at(0) == 'D') {  // DIN symbol
+    if (Props.back()->Value.at(0) == 'D') {  // DIN symbol
         xl = -15;
         xr = 15;
         Lines.append(new qucs::Line(15, -y, 15, y, QPen(Qt::darkBlue, 2)));
@@ -1764,7 +1776,7 @@ Component *getComponentFromName(QString &Line, Schematic *p) {
     else if (cstr.left(6) == "SPfile" && cstr != "SPfile") {
         // backward compatible
         c = new SParamFile();
-        c->Props.getLast()->Value = cstr.mid(6);
+        c->Props.back()->Value = cstr.mid(6);
     } else
         c = Module::getComponent(cstr);
 
diff --git a/qucs/components/component.h b/qucs/components/component.h
index da1e7f2c..cc98bd09 100644
--- a/qucs/components/component.h
+++ b/qucs/components/component.h
@@ -23,7 +23,8 @@
 // builds fail without explicit QObject inclusion
 #include <QObject>
 #include "extsimkernels/spicecompat.h"
-#include "qt3_compat/qt_compat.h"
+
+#include <QList>
 
 #include "element.h"
 
@@ -90,7 +91,7 @@ class Component : public Element {
   QList<qucs::Ellips *>     Ellipses;
   QList<Port *>     Ports;
   QList<Text *>     Texts;
-  Q3PtrList<Property> Props;
+  QList<Property*> Props;
 
   #define COMP_IS_OPEN    0
   #define COMP_IS_ACTIVE  1
@@ -109,6 +110,7 @@ class Component : public Element {
   QPen WrongSimulatorPen;
 
   void paintIcon(QPixmap *pixmap);
+  Property * getProperty(const QString&);
 
 protected:
   virtual QString netlist();
@@ -125,7 +127,6 @@ class Component : public Element {
   bool getBrush(const QString&, QBrush&, int);
 
   void copyComponent(Component*);
-  Property * getProperty(const QString&);
   Schematic* containingSchematic;
 
   virtual void drawSymbol(QPainter* p);
diff --git a/qucs/components/componentdialog.cpp b/qucs/components/componentdialog.cpp
index 42ddee3a..50973c0d 100644
--- a/qucs/components/componentdialog.cpp
+++ b/qucs/components/componentdialog.cpp
@@ -56,6 +56,8 @@ ComponentDialog::ComponentDialog(Component *c, Schematic *d)
   QString s;
   setAllVisible = true; // state when toggling properties visibility
 
+  compIsSimulation = false;
+
   all = new QVBoxLayout; // to provide necessary size
   this->setLayout(all);
   all->setContentsMargins(1,1,1,1);
@@ -72,10 +74,14 @@ ComponentDialog::ComponentDialog(Component *c, Schematic *d)
   Expr.setPattern("[A-Za-z][A-Za-z0-9_]+");
   ValName = new QRegularExpressionValidator(Expr,this);
 
-  checkSim  = 0;  comboSim  = 0;  comboType  = 0;  checkParam = 0;
-  editStart = 0;  editStop = 0;  editNumber = 0;
+  checkSim  = nullptr;  comboSim  = nullptr;
+  comboType  = nullptr;  checkParam = nullptr;
+  editStart = nullptr;  editStop = nullptr;
+  editNumber = nullptr;
   
-  Property *pp = 0; // last property shown elsewhere outside the properties table, not to put in TableView
+  // last property shown elsewhere outside the properties table, not to put in TableView
+  auto pp = Comp->Props.begin();
+
   // ...........................................................
   // if simulation component: .TR, .AC, .SW, (.SP ?)
   if((Comp->Model[0] == '.') &&
@@ -85,6 +91,7 @@ ComponentDialog::ComponentDialog(Component *c, Schematic *d)
      (Comp->Model != ".PZ") && (Comp->Model != ".SENS") &&
      (Comp->Model != ".SENS_AC") && (Comp->Model != ".SENS_XYCE") &&
      (Comp->Model != ".SENS_TR_XYCE")) {
+    compIsSimulation = true;
     QTabWidget *t = new QTabWidget(this);
     all->addWidget(t);
 
@@ -197,33 +204,35 @@ ComponentDialog::ComponentDialog(Component *c, Schematic *d)
           if(pc->Model[0] == '.')
             comboSim->insertItem(comboSim->count(), pc->Name);
       }
-      qDebug() << "[]" << Comp->Props.first()->Value;
+      qDebug() << "[]" << (*pp)->Value;
       // set selected simulations in combo box to the currently used one
-      int i = comboSim->findText(Comp->Props.first()->Value);
+      int i = comboSim->findText((*pp)->Value);
       if (i != -1) // current simulation is in the available simulations list (normal case)
 	comboSim->setCurrentIndex(i);
       else  // current simulation not in the available simulations list
-	comboSim->setEditText(Comp->Props.first()->Value);
-
-      checkSim->setChecked(Comp->Props.current()->display);
-      s = Comp->Props.next()->Value;
-      checkType->setChecked(Comp->Props.current()->display);
-      editParam->setText(Comp->Props.next()->Value);
-      checkParam->setChecked(Comp->Props.current()->display);
+        comboSim->setEditText((*pp)->Value);
+
+      checkSim->setChecked((*pp)->display);
+      ++pp;
+      s = (*pp)->Value;
+      checkType->setChecked((*pp)->display);
+      ++pp;
+      editParam->setText((*pp)->Value);
+      checkParam->setChecked((*pp)->display);
     }
     else {
-      s = Comp->Props.first()->Value;
-      checkType->setChecked(Comp->Props.current()->display);
+      s = (*pp)->Value;
+      checkType->setChecked((*pp)->display);
     }
-    pp = Comp->Props.next();
-    editStart->setText(pp->Value);
-    checkStart->setChecked(pp->display);
-    pp = Comp->Props.next();
-    editStop->setText(pp->Value);
-    checkStop->setChecked(pp->display);
-    pp = Comp->Props.next();  // remember last property for ListView
-    editNumber->setText(pp->Value);
-    checkNumber->setChecked(pp->display);
+    ++pp;
+    editStart->setText((*pp)->Value);
+    checkStart->setChecked((*pp)->display);
+    ++pp;
+    editStop->setText((*pp)->Value);
+    checkStop->setChecked((*pp)->display);
+    ++pp;  // remember last property for ListView
+    editNumber->setText((*pp)->Value);
+    checkNumber->setChecked((*pp)->display);
 
     int tNum = 0;
     if(s[0] == 'l') {
@@ -240,10 +249,11 @@ ComponentDialog::ComponentDialog(Component *c, Schematic *d)
     if(tNum > 1) {
       editValues->setText(
 		editNumber->text().mid(1, editNumber->text().length()-2));
-      checkValues->setChecked(Comp->Props.current()->display);
+      checkValues->setChecked((*pp)->display);
       editNumber->setText("2");
     }
     slotNumberChanged(0);
+    ++pp;
 
 /*    connect(editValues, SIGNAL(textChanged(const QString&)),
 	    SLOT(slotTextChanged(const QString&)));*/
@@ -449,34 +459,34 @@ ComponentDialog::ComponentDialog(Component *c, Schematic *d)
 
   /*! Insert all \a Comp properties into the dialog \a prop list */
   int row=0; // row counter
-  for(Property *p = Comp->Props.at(Comp->Props.find(pp)+1); p != 0; p = Comp->Props.next()) {
+  for(auto p = pp; p != Comp->Props.end(); ++p) {
 
       // do not insert if already on first tab
       // this is the reason it was originally from back to front...
       // the 'pp' is the lasted property stepped over while filling the Swep tab
   //    if(p == pp)
   //      break;
-      if(p->display)
+      if((*p)->display)
         s = tr("yes");
       else
         s = tr("no");
 
       // add Props into TableWidget
-      qDebug() << " Loading Comp->Props :" << p->Name << p->Value << p->display << p->Description ;
+      qDebug() << " Loading Comp->Props :" << (*p)->Name << (*p)->Value << (*p)->display << (*p)->Description ;
 
       prop->setRowCount(prop->rowCount()+1);
 
       QTableWidgetItem *cell;
-      cell = new QTableWidgetItem(p->Name);
+      cell = new QTableWidgetItem((*p)->Name);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 0, cell);
-      cell = new QTableWidgetItem(p->Value);
+      cell = new QTableWidgetItem((*p)->Value);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 1, cell);
       cell = new QTableWidgetItem(s);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 2, cell);
-      cell = new QTableWidgetItem(p->Description);
+      cell = new QTableWidgetItem((*p)->Description);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 3, cell);
 
@@ -541,36 +551,37 @@ void ComponentDialog::updateCompPropsList()
     QString s;
     int row=0; // row counter
     //for(Property *p = Comp->Props.first(); p != 0; p = Comp->Props.next()) {
-    for(Property *p = Comp->Props.at(last_prop); p != 0; p = Comp->Props.next()) {
+    auto &p = Comp->Props;
+    for(int i = last_prop; i< p.size();i++) {
 
       // do not insert if already on first tab
       // this is the reason it was originally from back to front...
       // the 'pp' is the lasted property stepped over while filling the Swep tab
   //    if(p == pp)
   //      break;
-      if(p->display)
+      if(p.at(i)->display)
         s = tr("yes");
       else
         s = tr("no");
 
       // add Props into TableWidget
-      qDebug() << " Loading Comp->Props :" << p->Name << p->Value << p->display << p->Description ;
+      qDebug() << " Loading Comp->Props :" << p.at(i)->Name << p.at(i)->Value << p.at(i)->display << p.at(i)->Description ;
 
       if (row > prop->rowCount()-1) { // Add new rows
           prop->setRowCount(prop->rowCount()+1);
       }
 
       QTableWidgetItem *cell;
-      cell = new QTableWidgetItem(p->Name);
+      cell = new QTableWidgetItem(p.at(i)->Name);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 0, cell);
-      cell = new QTableWidgetItem(p->Value);
+      cell = new QTableWidgetItem(p.at(i)->Value);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 1, cell);
       cell = new QTableWidgetItem(s);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 2, cell);
-      cell = new QTableWidgetItem(p->Description);
+      cell = new QTableWidgetItem(p.at(i)->Description);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 3, cell);
 
@@ -878,14 +889,13 @@ void ComponentDialog::slotApplyInput()
 
   QString tmp;
   Component *pc;
-  if(CompNameEdit->text().isEmpty())  CompNameEdit->setText(Comp->Name);
-  else
-  if(CompNameEdit->text() != Comp->Name) {
-    for(pc = Doc->Components->first(); pc!=0; pc = Doc->Components->next())
-      if(pc->Name == CompNameEdit->text())
-        break;  // found component with the same name ?
-    if(pc)  CompNameEdit->setText(Comp->Name);
-    else {
+  if (CompNameEdit->text().isEmpty()) {
+    CompNameEdit->setText(Comp->Name);
+  } else if(CompNameEdit->text() != Comp->Name) {
+    pc = Doc->getComponentByName(CompNameEdit->text());
+    if (pc != nullptr) {
+      CompNameEdit->setText(Comp->Name);
+    } else {
       Comp->Name = CompNameEdit->text();
       changed = true;
     }
@@ -896,201 +906,122 @@ void ComponentDialog::slotApplyInput()
    *  The pointers to the combo, edits,... are set to 0.
    *  Only check if the widgets were created (pointers checks are 'true')
    */
-  bool display;
-  Property *pp = Comp->Props.first();
+  //auto pp = Comp->Props.begin();
   // apply all the new property values
+  int idxStart = 1;
+  if (Comp->Model == ".SW") {
+    idxStart = 3;
+  }
 
-  if(comboSim) {
-    display = checkSim->isChecked();
-    if(pp->display != display) {
-      pp->display = display;
-      changed = true;
-    }
-    if(pp->Value != comboSim->currentText()) {
-      pp->Value = comboSim->currentText();
-      changed = true;
-    }
-    pp = Comp->Props.next();
+  if(comboSim != nullptr) {
+    auto pp = Comp->getProperty("Sim");
+    bool display = checkSim->isChecked();
+    QString value = comboSim->currentText();
+    updateProperty(pp,value,display);
   }
-  if(comboType) {
-    display = checkType->isChecked();
-    if(pp->display != display) {
-      pp->display = display;
-      changed = true;
-    }
+  if(comboType != nullptr) {
+    bool display = checkType->isChecked();
+    auto pp = Comp->getProperty("Type");
     switch(comboType->currentIndex()) {
       case 1:  tmp = "log";   break;
       case 2:  tmp = "list";  break;
       case 3:  tmp = "const"; break;
       default: tmp = "lin";   break;
     }
-    if(pp->Value != tmp) {
-      pp->Value = tmp;
-      changed = true;
-    }
-    pp = Comp->Props.next();
+    updateProperty(pp,tmp,display);
   }
-  if(checkParam) if(checkParam->isEnabled()) {
-    display = checkParam->isChecked();
-    if(pp->display != display) {
-      pp->display = display;
-      changed = true;
+  if(checkParam != nullptr) {
+    if(checkParam->isEnabled()) {
+      auto pp = Comp->getProperty("Param");
+      bool display = checkParam->isChecked();
+      QString value = editParam->text();
+      updateProperty(pp,value,display);
     }
-    if(pp->Value != editParam->text()) {
-      pp->Value = editParam->text();
-      changed = true;
-    }
-    pp = Comp->Props.next();
   }
-  if(editStart) {
-    if(comboType->currentIndex() < 2) {
-      display = checkStart->isChecked();
-      if(pp->display != display) {
-        pp->display = display;
-        changed = true;
-      }
-      pp->Name  = "Start";
-      if(pp->Value != editStart->text()) {
-        pp->Value = editStart->text();
-        changed = true;
-      }
-      pp = Comp->Props.next();
-
+  if(editStart != nullptr) {
+    if(comboType->currentIndex() < 2 ) {
+      Property *pp = Comp->Props.at(idxStart); // Start
+      bool display = checkStart->isChecked();
+      QString value = editStart->text();
+      updateProperty(pp,value,display);
+      pp->Name = "Start";
+
+      pp = Comp->Props.at(idxStart+1); // Stop
       display = checkStop->isChecked();
-      if(pp->display != display) {
-        pp->display = display;
-        changed = true;
+      value = editStop->text();
+      updateProperty(pp,value,display);
+      pp->Name = "Stop";
+
+      pp = Comp->Props.at(idxStart+2);
+      if (pp != nullptr) { // Points/Values
+        display = checkNumber->isChecked();
+        value = editNumber->text();
+        updateProperty(pp,value,display);
+        if (changed) pp->Name = "Points";
       }
-      pp->Name  = "Stop";
-      if(pp->Value != editStop->text()) {
-        pp->Value = editStop->text();
-        changed = true;
-      }
-      pp = Comp->Props.next();
-
-      display = checkNumber->isChecked();
-      if(pp->display != display) {
-        pp->display = display;
-        changed = true;
-      }
-      if((pp->Value != editNumber->text()) || (pp->Name != "Points")) {
-        pp->Value = editNumber->text();
-        pp->Name  = "Points";
-        changed = true;
-      }
-      qDebug() << "====> before ad"
-               << pp->Description;
-
-      pp = Comp->Props.next();
-    }
-    else {
+      qDebug() << "====> before ad";
+    } else {
       // If a value list is used, the properties "Start" and "Stop" are not
       // used. -> Call them "Symbol" to omit them in the netlist.
+      Property *pp = Comp->Props.at(idxStart);
       pp->Name = "Symbol";
       pp->display = false;
-      pp = Comp->Props.next();
+      pp = Comp->Props.at(idxStart+1);
       pp->Name = "Symbol";
       pp->display = false;
-      pp = Comp->Props.next();
 
-      display = checkValues->isChecked();
+      pp = Comp->Props.at(idxStart+2);
+      bool display = checkValues->isChecked();
+      QString value = "["+editValues->text()+"]";
+
       if(pp->display != display) {
         pp->display = display;
         changed = true;
       }
-      tmp = "["+editValues->text()+"]";
-      if((pp->Value != tmp) || (pp->Name != "Values")) {
-        pp->Value = tmp;
+      if(pp->Value != value || pp->Name != "Values") {
+        pp->Value = value;
         pp->Name  = "Values";
         changed = true;
       }
-      qDebug() << "====> before ad"
-               << pp;
-
-      pp = Comp->Props.next();
     }
   }
 
 
   // pick selected row
-  QTableWidgetItem *item = 0;
+  QTableWidgetItem *item = nullptr;
 
   //  make sure we have one item, take selected
-  if (prop->selectedItems().size()) {
+  if (prop->selectedItems().size() != 0) {
     item = prop->selectedItems()[0];
   }
 
   /*! Walk the dialog list of 'prop'
    */
-   if(item != 0) {
-     int row = item->row();
-     QString name  = prop->item(row, 0)->text();
-     QString value = prop->item(row, 1)->text();
+  if(item != nullptr) {
+    int row = item->row();
+    QString name  = prop->item(row, 0)->text();
+    QString value = prop->item(row, 1)->text();
 
-     // apply edit line
-     if(value != edit->text())
-       prop->item(row, 1)->setText(edit->text());
+           // apply edit line
+    if(value != edit->text()) {
+      prop->item(row, 1)->setText(edit->text());
+    }
 
-     // apply property name
-     if (!NameEdit->isHidden())
-       if (name != NameEdit->text())
-         prop->item(row, 0)->setText(NameEdit->text());
-
-     // apply all the new property values in the ListView
-     for( int row = 0; row < prop->rowCount(); row++ ) {
-
-       QString name  = prop->item(row, 0)->text();
-       QString value = prop->item(row, 1)->text();
-       QString disp = prop->item(row, 2)->text();
-       QString desc = prop->item(row, 3)->text();
-
-       qDebug() << "====>" <<name << value
-                << Comp->Props.count()
-                << prop->rowCount() +1
-                << pp;
-
-       display = (disp == tr("yes"));
-       if( pp ) {
-
-         if(pp->display != display) {
-             pp->display = display;
-             changed = true;
-         }
-         if(pp->Value != value) {
-            pp->Value = value;
-            changed = true;
-         }
-         if(pp->Name != name) {
-           pp->Name = name;   // override if previous one was removed
-           changed = true;
-         }
-         pp->Description = desc;
-         }
-       else {
-         // if properties where added in the dialog
-         // -> create new on the Comp
-         Q_ASSERT(prop->rowCount() >= 0);
-         if ( (int) Comp->Props.count() < prop->rowCount() +1) {
-             qDebug() << "adding to Comp ";
-             Comp->Props.append(new Property(name, value, display, desc));
-             changed = true;
-         }
+    // apply property name
+    if (!NameEdit->isHidden()) {
+      if (name != NameEdit->text()) {
+        prop->item(row, 0)->setText(NameEdit->text());
+      }
     }
-    pp = Comp->Props.next();
   }
 
-  // original Comp still has properties? (removed some in the dialog?)
-  // if more properties than in ListView -> delete the rest
-  if(pp) {
-    pp = Comp->Props.prev();
-    Comp->Props.last();
-    while(pp != Comp->Props.current())
-      Comp->Props.remove();
-    changed = true;
+  // apply all the new property values in the ListView
+  if (Comp->isEquation) {
+    recreatePropsFromTable();
+  } else {
+    fillPropsFromTable();
   }
 
- } // end if (item !=0)
-
   if(changed) {
     int dx, dy;
     Comp->textSize(dx, dy);
@@ -1584,3 +1515,80 @@ void ComponentDialog::slotFillFromSpice()
   }
   delete dlg;
 }
+
+
+void ComponentDialog::fillPropsFromTable()
+{
+  for( int row = 0; row < prop->rowCount(); row++ ) {
+    QString name  = prop->item(row, 0)->text();
+    QString value = prop->item(row, 1)->text();
+    QString disp = prop->item(row, 2)->text();
+    QString desc = prop->item(row, 3)->text();
+    bool display = (disp == tr("yes"));
+    auto pp = Comp->getProperty(name);
+    updateProperty(pp,value,display);
+  }
+}
+
+void ComponentDialog::recreatePropsFromTable()
+{
+  if (!Comp->isEquation) return; // add / remove properties allowed only for equations
+
+  if (Comp->Props.size() != prop->rowCount()) {
+    changed = true; // Added or removed properties
+  } else {
+    for( int row = 0; row < prop->rowCount(); row++ ) {
+      QString name  = prop->item(row, 0)->text();
+      QString value = prop->item(row, 1)->text();
+      QString disp = prop->item(row, 2)->text();
+      bool display = (disp == tr("yes"));
+      auto pp = Comp->Props.at(row);
+      if ((pp->Name != name) || (pp->Value != value) ||
+          (pp->display != display)) {
+        changed = true; // reordered or edited properties
+        break;
+      }
+    }
+  }
+
+  if (!changed) {
+    return;
+  }
+
+  for (auto pp: Comp->Props) {
+    delete pp;
+    pp = nullptr;
+  }
+  Comp->Props.clear();
+  for( int row = 0; row < prop->rowCount(); row++ ) {
+    QString name  = prop->item(row, 0)->text();
+    QString value = prop->item(row, 1)->text();
+    QString disp = prop->item(row, 2)->text();
+    QString desc = prop->item(row, 3)->text();
+    bool display = (disp == tr("yes"));
+
+    Property *pp = new Property;
+    pp->Name = name;
+    pp->Value = value;
+    pp->display = display;
+    pp->Description = desc;
+    Comp->Props.append(pp);
+  }
+}
+
+
+bool ComponentDialog::propChanged(Property *pp, const QString &value, const bool display)
+{
+  if (pp->Value != value) return true;
+  if (pp->display != display) return true;
+  return false;
+}
+
+void ComponentDialog::updateProperty(Property *pp, const QString &value, const bool display)
+{
+  if (propChanged(pp,value,display)) {
+    pp->Value = value;
+    pp->display = display;
+    changed = true;
+  }
+}
diff --git a/qucs/components/componentdialog.h b/qucs/components/componentdialog.h
index fc459914..194b2b95 100644
--- a/qucs/components/componentdialog.h
+++ b/qucs/components/componentdialog.h
@@ -100,6 +100,7 @@ protected slots:
   bool        changed;
   int         tx_Dist, ty_Dist;   // remember the text position
   bool        setAllVisible; // used for toggling visibility of properties
+  bool compIsSimulation;
  
   QLabel    *textType;
   QLabel    *textSim, *textParam, *textValues, *textStart, *textStop,
@@ -112,6 +113,11 @@ protected slots:
 
   void updateCompPropsList(void);
   QStringList getSimulationList();
+
+  void fillPropsFromTable();
+  void recreatePropsFromTable();
+  bool propChanged(Property *pp, const QString &value, const bool display);
+  void updateProperty(Property *pp, const QString &value, const bool display);
 };
 
 #endif
diff --git a/qucs/components/dff_SR.cpp b/qucs/components/dff_SR.cpp
index 2bf88255..2f1463d7 100644
--- a/qucs/components/dff_SR.cpp
+++ b/qucs/components/dff_SR.cpp
@@ -44,7 +44,8 @@ dff_SR::dff_SR()
 Component * dff_SR::newOne()
 {
   dff_SR * p = new dff_SR();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/digi_source.cpp b/qucs/components/digi_source.cpp
index 608c2d81..8ff0518a 100644
--- a/qucs/components/digi_source.cpp
+++ b/qucs/components/digi_source.cpp
@@ -90,13 +90,14 @@ QString Digi_Source::netlist()
   s += " "+Ports.first()->Connection->Name;
   
   // output all properties
-  Props.first();   // first property not needed
-  Property *pp = Props.next();
-  s += " "+pp->Name+"=\""+pp->Value+"\"";
-  pp = Props.next();
-  s += " "+pp->Name+"=\"["+pp->Value+"]\"";
-  pp = Props.next();
-  s += " "+pp->Name+"=\""+pp->Value+"\"\n";
+     // first property not needed
+  auto pp = Props.begin();
+  pp++;
+  s += " "+(*pp)->Name+"=\""+(*pp)->Value+"\"";
+  pp++;
+  s += " "+(*pp)->Name+"=\"["+(*pp)->Value+"]\"";
+  pp++;
+  s += " "+(*pp)->Name+"=\""+(*pp)->Value+"\"\n";
 
   return s;
 }
@@ -165,7 +166,8 @@ QString Digi_Source::verilogCode(int NumPorts)
       State = '1';
     s += "  always begin\n";
 
-    t = Props.next()->Value.section(';',z,z).trimmed();
+    QString pv = Props.at(2)->Value;
+    t = pv.section(';',z,z).trimmed();
     while(!t.isEmpty()) {
       if(!misc::Verilog_Delay(t, Name))
         return t;    // time has not VHDL format
@@ -173,11 +175,11 @@ QString Digi_Source::verilogCode(int NumPorts)
       s += "   " + t + ";\n";
       State ^= 1;
       z++;
-      t = Props.current()->Value.section(';',z,z).trimmed();
+      t = pv.section(';',z,z).trimmed();
     }
   }
   else {  // truth table simulation
-    int Num = Props.getFirst()->Value.toInt() - 1;    
+    int Num = Props.front()->Value.toInt() - 1;    
     s += "  always begin\n";
     s += "    " + r + " = 0;\n";
     s += "    #"+ QString::number(1 << Num) + ";\n";
diff --git a/qucs/components/diode.cpp b/qucs/components/diode.cpp
index 832325f7..a9eef7b3 100644
--- a/qucs/components/diode.cpp
+++ b/qucs/components/diode.cpp
@@ -167,12 +167,12 @@ Element* Diode::info(QString& Name, char* &BitmapFile, bool getNewOne)
 // -------------------------------------------------------
 void Diode::createSymbol()
 {
-  if(Props.getLast()->Value.at(0) == 'V') {
+  if(Props.back()->Value.at(0) == 'V') {
     Lines.append(new qucs::Line(-30,  0, -9,  0,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line( -6,  0, 30,  0,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line( -9, -9, -9,  9,QPen(Qt::darkBlue,2)));
   }
-  else if(Props.getLast()->Value.at(0) == 'U') {
+  else if(Props.back()->Value.at(0) == 'U') {
     Lines.append(new qucs::Line(-30,  0, -6,  0,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line(  6,  0, 30,  0,QPen(Qt::darkBlue,2)));
   }
@@ -184,11 +184,11 @@ void Diode::createSymbol()
   Lines.append(new qucs::Line( -6,  0,  6, -9,QPen(Qt::darkBlue,2)));
   Lines.append(new qucs::Line( -6,  0,  6,  9,QPen(Qt::darkBlue,2)));
 
-  if(Props.getLast()->Value.at(0) == 'S') {
+  if(Props.back()->Value.at(0) == 'S') {
     Lines.append(new qucs::Line( -6, -9,-12,-12,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line( -6,  9,  0, 12,QPen(Qt::darkBlue,2)));
   }
-  else if(Props.getLast()->Value.at(0) == 'Z') {
+  else if(Props.back()->Value.at(0) == 'Z') {
     Lines.append(new qucs::Line( -6, 9, -1, 9,QPen(Qt::darkBlue,2)));
   }
 
diff --git a/qucs/components/dmux2to4.cpp b/qucs/components/dmux2to4.cpp
index 65c49c2f..a7a3c745 100644
--- a/qucs/components/dmux2to4.cpp
+++ b/qucs/components/dmux2to4.cpp
@@ -40,7 +40,7 @@ dmux2to4::dmux2to4()
 Component * dmux2to4::newOne()
 {
   dmux2to4 * p = new dmux2to4();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/dmux3to8.cpp b/qucs/components/dmux3to8.cpp
index 076c21e4..e85c3303 100644
--- a/qucs/components/dmux3to8.cpp
+++ b/qucs/components/dmux3to8.cpp
@@ -41,7 +41,7 @@ dmux3to8::dmux3to8()
 Component * dmux3to8::newOne()
 {
   dmux3to8 * p = new dmux3to8();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/dmux4to16.cpp b/qucs/components/dmux4to16.cpp
index 15f38691..088dd831 100644
--- a/qucs/components/dmux4to16.cpp
+++ b/qucs/components/dmux4to16.cpp
@@ -40,7 +40,7 @@ dmux4to16::dmux4to16()
 Component * dmux4to16::newOne()
 {
   dmux4to16 * p = new dmux4to16();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/ecvs.cpp b/qucs/components/ecvs.cpp
index a8b69222..4ed58745 100644
--- a/qucs/components/ecvs.cpp
+++ b/qucs/components/ecvs.cpp
@@ -100,7 +100,7 @@ QString ecvs::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output all properties
-  for(Property *p2 = Props.first(); p2 != 0; p2 = Props.next())
+  for(Property *p2 : Props)
     s += " "+p2->Name+"=\""+p2->Value+"\"";
 
   return s + "\n";
diff --git a/qucs/components/eqndefined.cpp b/qucs/components/eqndefined.cpp
index 63159320..ed759931 100644
--- a/qucs/components/eqndefined.cpp
+++ b/qucs/components/eqndefined.cpp
@@ -87,12 +87,10 @@ QString EqnDefined::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output all properties
-  Property *p2 = Props.at(2);
-  while(p2) {
-    s += " "+p2->Name+"=\""+Name+"."+p2->Name+"\"";
-    e += "  Eqn:Eqn"+Name+p2->Name+" "+
-      Name+"."+p2->Name+"=\""+p2->Value+"\" Export=\"no\"\n";
-    p2 = Props.next();
+  for(int i = 2;i<Props.size();i++) {
+    s += " "+Props.at(i)->Name+"=\""+Name+"."+Props.at(i)->Name+"\"";
+    e += "  Eqn:Eqn"+Name+Props.at(i)->Name+" "+
+      Name+"."+Props.at(i)->Name+"=\""+Props.at(i)->Value+"\" Export=\"no\"\n";
   }
 
   return s+e;
@@ -291,12 +289,13 @@ void EqnDefined::createSymbol()
   }
 
   // adjust property names
-  Property * p1 = Props.at(2);
+  auto  p1 = Props.begin();
+  std::advance(p1, 2);
   for(i = 1; i <= Num; i++) {
-    p1->Name = "I"+QString::number(i);
-    p1 = Props.next();
-    p1->Name = "Q"+QString::number(i);
-    p1 = Props.next();
+    (*p1)->Name = "I"+QString::number(i);
+    p1++;
+    (*p1)->Name = "Q"+QString::number(i);
+    p1++;
   }
 
   // draw symbol
diff --git a/qucs/components/equation.cpp b/qucs/components/equation.cpp
index 8adce4e3..108428c3 100644
--- a/qucs/components/equation.cpp
+++ b/qucs/components/equation.cpp
@@ -63,7 +63,7 @@ QString Equation::verilogCode(int)
 {
   QString s;
   // output all equations
-  for(Property *pr = Props.first(); pr != 0; pr = Props.next())
+  for(Property *pr : Props)
     if(pr->Name != "Export")
       s += "  real "+pr->Name+"; initial "+pr->Name+" = "+pr->Value+";\n";
   return s;
@@ -74,7 +74,7 @@ QString Equation::vhdlCode(int)
 {
   QString s;
   // output all equations
-  for(Property *pr = Props.first(); pr != 0; pr = Props.next())
+  for(Property *pr : Props)
     if(pr->Name != "Export")
       s += "  constant "+pr->Name+" : time := "+pr->Value+";\n";
   return s;
diff --git a/qucs/components/fa1b.cpp b/qucs/components/fa1b.cpp
index a03c3219..71bb55fb 100644
--- a/qucs/components/fa1b.cpp
+++ b/qucs/components/fa1b.cpp
@@ -40,7 +40,7 @@ fa1b::fa1b()
 Component * fa1b::newOne()
 {
   fa1b * p = new fa1b();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/fa2b.cpp b/qucs/components/fa2b.cpp
index 128a53d5..a54326c6 100644
--- a/qucs/components/fa2b.cpp
+++ b/qucs/components/fa2b.cpp
@@ -41,7 +41,7 @@ fa2b::fa2b()
 Component * fa2b::newOne()
 {
   fa2b * p = new fa2b();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/gatedDlatch.cpp b/qucs/components/gatedDlatch.cpp
index 69e7dc4d..8818df90 100644
--- a/qucs/components/gatedDlatch.cpp
+++ b/qucs/components/gatedDlatch.cpp
@@ -42,7 +42,7 @@ gatedDlatch::gatedDlatch()
 Component * gatedDlatch::newOne()
 {
   gatedDlatch * p = new gatedDlatch();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/greytobinary4bit.cpp b/qucs/components/greytobinary4bit.cpp
index 6840d32f..8f6c75bb 100644
--- a/qucs/components/greytobinary4bit.cpp
+++ b/qucs/components/greytobinary4bit.cpp
@@ -41,7 +41,7 @@ greytobinary4bit::greytobinary4bit()
 Component * greytobinary4bit::newOne()
 {
   greytobinary4bit * p = new greytobinary4bit();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/ha1b.cpp b/qucs/components/ha1b.cpp
index c5370f15..7409a808 100644
--- a/qucs/components/ha1b.cpp
+++ b/qucs/components/ha1b.cpp
@@ -40,7 +40,7 @@ ha1b::ha1b()
 Component * ha1b::newOne()
 {
   ha1b * p = new ha1b();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/hpribin4bit.cpp b/qucs/components/hpribin4bit.cpp
index 3a7ab438..2ba5ef4f 100644
--- a/qucs/components/hpribin4bit.cpp
+++ b/qucs/components/hpribin4bit.cpp
@@ -40,7 +40,7 @@ hpribin4bit::hpribin4bit()
 Component * hpribin4bit::newOne()
 {
   hpribin4bit * p = new hpribin4bit();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/ifile.cpp b/qucs/components/ifile.cpp
index 7ef96650..1cf4dac7 100644
--- a/qucs/components/ifile.cpp
+++ b/qucs/components/ifile.cpp
@@ -86,7 +86,7 @@ Element* iFile::info(QString& Name, char* &BitmapFile, bool getNewOne)
 QString iFile::getSubcircuitFile()
 {
   // construct full filename
-  QString FileName = Props.getFirst()->Value;
+  QString FileName = Props.front()->Value;
   return misc::properAbsFileName(FileName);
 }
 
@@ -100,12 +100,11 @@ QString iFile::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output file properties
-  Property *p2 = Props.first();
-  s += " "+p2->Name+"=\"{"+getSubcircuitFile()+"}\"";
+  s += " "+Props.at(0)->Name+"=\"{"+getSubcircuitFile()+"}\"";
 
   // output all remaining properties
-  for(p2 = Props.next(); p2 != 0; p2 = Props.next())
-    s += " "+p2->Name+"=\""+p2->Value+"\"";
+  for(int i = 1; i < Props.size();i++)
+    s += " "+Props.at(i)->Name+"=\""+Props.at(i)->Value+"\"";
 
   return s + "\n";
 }
diff --git a/qucs/components/jfet.cpp b/qucs/components/jfet.cpp
index 4cfc0511..312c8b3f 100644
--- a/qucs/components/jfet.cpp
+++ b/qucs/components/jfet.cpp
@@ -87,7 +87,7 @@ JFET::JFET() {
 Component* JFET::newOne()
 {
   JFET* p = new JFET();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0);
   return p;
 }
@@ -147,7 +147,7 @@ Element* JFET::info_p(QString& Name, char* &BitmapFile, bool getNewOne)
 
   if(getNewOne) {
     JFET* p = new JFET();
-    p->Props.getFirst()->Value = "pfet";
+    p->Props.front()->Value = "pfet";
     p->recreate(0);
     return p;
   }
@@ -166,7 +166,7 @@ void JFET::createSymbol()
 
   Lines.append(new qucs::Line( -4, 24,  4, 20,QPen(Qt::darkBlue,2)));
 
-  if(Props.getFirst()->Value == "nfet") {
+  if(Props.front()->Value == "nfet") {
     Lines.append(new qucs::Line(-16, -5,-11,  0,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line(-16,  5,-11,  0,QPen(Qt::darkBlue,2)));
   }
diff --git a/qucs/components/jkff_SR.cpp b/qucs/components/jkff_SR.cpp
index 02805947..ab960661 100644
--- a/qucs/components/jkff_SR.cpp
+++ b/qucs/components/jkff_SR.cpp
@@ -44,7 +44,7 @@ jkff_SR::jkff_SR()
 Component * jkff_SR::newOne()
 {
   jkff_SR * p = new jkff_SR();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/libcomp.cpp b/qucs/components/libcomp.cpp
index 96ec0425..eab40cd5 100644
--- a/qucs/components/libcomp.cpp
+++ b/qucs/components/libcomp.cpp
@@ -49,8 +49,8 @@ LibComp::LibComp()
 Component* LibComp::newOne()
 {
   LibComp *p = new LibComp();
-  p->Props.first()->Value = Props.first()->Value;
-  p->Props.next()->Value = Props.next()->Value;
+  p->Props.at(0)->Value = Props.at(0)->Value;
+  p->Props.at(1)->Value = Props.at(1)->Value;
   p->recreate(0);
   return p;
 }
@@ -87,7 +87,7 @@ int LibComp::loadSection(const QString& Name, QString& Section,
              QStringList *Includes, QStringList *Attach)
 {
   QDir Directory(QucsSettings.LibDir);
-  QFile file(misc::properAbsFileName(Directory.absoluteFilePath(Props.first()->Value + ".lib"), containingSchematic));
+  QFile file(misc::properAbsFileName(Directory.absoluteFilePath(Props.at(0)->Value + ".lib"), containingSchematic));
   if(!file.open(QIODevice::ReadOnly))
     return -1;
 
@@ -123,7 +123,7 @@ int LibComp::loadSection(const QString& Name, QString& Section,
   }
 
   // search component
-  Line = "\n<Component " + Props.next()->Value + ">";
+  Line = "\n<Component " + Props.at(1)->Value + ">";
   Start = Section.indexOf(Line);
   if(Start < 0)  return -4;  // component not found
   Start = Section.indexOf('\n', Start);
@@ -207,13 +207,9 @@ int LibComp::loadSymbol()
     z = loadSection("Model", Line);
     if(z < 0)  return z;
 
-    Component *pc = getComponentFromName(Line);
-    if(pc == 0)  return -20;
-
-    copyComponent(pc);
-
-    pc->Props.setAutoDelete(false);
-    delete pc;
+    std::shared_ptr<Component> pc(getComponentFromName(Line));
+    if(!pc)  return -20;
+    copyComponent(pc.get());
 
     return 1;
   }
@@ -306,8 +302,8 @@ bool LibComp::createSubNetlist(QTextStream *stream, QStringList &FileList,
 // -------------------------------------------------------
 QString LibComp::createType()
 {
-  QString Type = misc::properFileName(Props.first()->Value);
-  return misc::properName(Type + "_" + Props.next()->Value);
+  QString Type = misc::properFileName(Props.at(0)->Value);
+  return misc::properName(Type + "_" + Props.at(1)->Value);
 }
 
 // -------------------------------------------------------
@@ -323,8 +319,8 @@ QString LibComp::netlist()
   s += " Type=\""+createType()+"\"";   // type for subcircuit
 
   // output user defined parameters
-  for(Property *pp = Props.at(2); pp != 0; pp = Props.next())
-    s += " "+pp->Name+"=\""+pp->Value+"\"";
+  for(int i = 2;i<Props.size();i++)
+    s += " "+Props.at(i)->Name+"=\""+Props.at(i)->Value+"\"";
 
   return s + '\n';
 }
@@ -373,9 +369,9 @@ QString LibComp::spice_netlist(bool)
     s += " " + createType();
 
     // output user defined parameters
-    for(Property *pp = Props.at(2); pp != 0; pp = Props.next()) {
-      QString val = spicecompat::normalize_value(pp->Value);
-      s += " "+pp->Name+"="+val;
+    for(int i = 2;i<Props.size();i++) {
+      QString val = spicecompat::normalize_value(Props.at(i)->Value);
+      s += " "+Props.at(i)->Name+"="+val;
     }
     s +="\n";
 
diff --git a/qucs/components/log_amp.cpp b/qucs/components/log_amp.cpp
index 9980c8a2..dc08e046 100644
--- a/qucs/components/log_amp.cpp
+++ b/qucs/components/log_amp.cpp
@@ -75,7 +75,7 @@ log_amp::log_amp()
 Component * log_amp::newOne()
 {
   log_amp * p = new log_amp();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/logic_0.cpp b/qucs/components/logic_0.cpp
index 3089d4d7..65e70d04 100644
--- a/qucs/components/logic_0.cpp
+++ b/qucs/components/logic_0.cpp
@@ -38,7 +38,7 @@ logic_0::logic_0()
 Component * logic_0::newOne()
 {
   logic_0 * p = new logic_0();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/logic_1.cpp b/qucs/components/logic_1.cpp
index 031e7d68..0469806b 100644
--- a/qucs/components/logic_1.cpp
+++ b/qucs/components/logic_1.cpp
@@ -37,7 +37,7 @@ logic_1::logic_1()
 Component * logic_1::newOne()
 {
   logic_1 * p = new logic_1();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 
diff --git a/qucs/components/logical_and.cpp b/qucs/components/logical_and.cpp
index d02b8a89..60430177 100644
--- a/qucs/components/logical_and.cpp
+++ b/qucs/components/logical_and.cpp
@@ -35,8 +35,8 @@ Logical_AND::~Logical_AND()
 Component* Logical_AND::newOne()
 {
   Logical_AND* p = new Logical_AND();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
-  p->Props.getLast()->Value = Props.getLast()->Value;
+  p->Props.front()->Value = Props.front()->Value;
+  p->Props.back()->Value = Props.back()->Value;
   p->recreate(0);
   return p;
 }
diff --git a/qucs/components/logical_buf.cpp b/qucs/components/logical_buf.cpp
index b99a4bbb..11d83b91 100644
--- a/qucs/components/logical_buf.cpp
+++ b/qucs/components/logical_buf.cpp
@@ -90,7 +90,7 @@ void Logical_Buf::createSymbol()
 {
   int xr;
 
-  if(Props.getLast()->Value.at(0) == 'D') {  // DIN symbol
+  if(Props.back()->Value.at(0) == 'D') {  // DIN symbol
     Lines.append(new qucs::Line( 15,-20, 15, 20,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line(-15,-20, 15,-20,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line(-15, 20, 15, 20,QPen(Qt::darkBlue,2)));
@@ -120,7 +120,7 @@ void Logical_Buf::createSymbol()
 Component* Logical_Buf::newOne()
 {
   Logical_Buf* p = new Logical_Buf();
-  p->Props.getLast()->Value = Props.getLast()->Value;
+  p->Props.back()->Value = Props.back()->Value;
   p->recreate(0);
   return p;
 }
diff --git a/qucs/components/logical_inv.cpp b/qucs/components/logical_inv.cpp
index 3625740d..4cc57be4 100644
--- a/qucs/components/logical_inv.cpp
+++ b/qucs/components/logical_inv.cpp
@@ -104,7 +104,7 @@ void Logical_Inv::createSymbol()
 {
   int xr;
 
-  if(Props.getLast()->Value.at(0) == 'D') {  // DIN symbol
+  if(Props.back()->Value.at(0) == 'D') {  // DIN symbol
     Lines.append(new qucs::Line( 15,-20, 15, 20,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line(-15,-20, 15,-20,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line(-15, 20, 15, 20,QPen(Qt::darkBlue,2)));
@@ -137,7 +137,7 @@ void Logical_Inv::createSymbol()
 Component* Logical_Inv::newOne()
 {
   Logical_Inv* p = new Logical_Inv();
-  p->Props.getLast()->Value = Props.getLast()->Value;
+  p->Props.back()->Value = Props.back()->Value;
   p->recreate(0);
   return p;
 }
diff --git a/qucs/components/logical_nand.cpp b/qucs/components/logical_nand.cpp
index 5e8fb63d..914e9dd4 100644
--- a/qucs/components/logical_nand.cpp
+++ b/qucs/components/logical_nand.cpp
@@ -35,8 +35,8 @@ Logical_NAND::~Logical_NAND()
 Component* Logical_NAND::newOne()
 {
   Logical_NAND* p = new Logical_NAND();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
-  p->Props.getLast()->Value = Props.getLast()->Value;
+  p->Props.front()->Value = Props.front()->Value;
+  p->Props.back()->Value = Props.back()->Value;
   p->recreate(0);
   return p;
 }
diff --git a/qucs/components/logical_nor.cpp b/qucs/components/logical_nor.cpp
index e881b758..fbb01b17 100644
--- a/qucs/components/logical_nor.cpp
+++ b/qucs/components/logical_nor.cpp
@@ -35,8 +35,8 @@ Logical_NOR::~Logical_NOR()
 Component* Logical_NOR::newOne()
 {
   Logical_NOR* p = new Logical_NOR();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
-  p->Props.getLast()->Value = Props.getLast()->Value;
+  p->Props.front()->Value = Props.front()->Value;
+  p->Props.back()->Value = Props.back()->Value;
   p->recreate(0);
   return p;
 }
diff --git a/qucs/components/logical_or.cpp b/qucs/components/logical_or.cpp
index 25993e0c..921f815e 100644
--- a/qucs/components/logical_or.cpp
+++ b/qucs/components/logical_or.cpp
@@ -35,8 +35,8 @@ Logical_OR::~Logical_OR()
 Component* Logical_OR::newOne()
 {
   Logical_OR* p = new Logical_OR();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
-  p->Props.getLast()->Value = Props.getLast()->Value;
+  p->Props.front()->Value = Props.front()->Value;
+  p->Props.back()->Value = Props.back()->Value;
   p->recreate(0);
   return p;
 }
diff --git a/qucs/components/logical_xnor.cpp b/qucs/components/logical_xnor.cpp
index 2fe424bf..4f9538cb 100644
--- a/qucs/components/logical_xnor.cpp
+++ b/qucs/components/logical_xnor.cpp
@@ -35,8 +35,8 @@ Logical_XNOR::~Logical_XNOR()
 Component* Logical_XNOR::newOne()
 {
   Logical_XNOR* p = new Logical_XNOR();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
-  p->Props.getLast()->Value = Props.getLast()->Value;
+  p->Props.front()->Value = Props.front()->Value;
+  p->Props.back()->Value = Props.back()->Value;
   p->recreate(0);
   return p;
 }
diff --git a/qucs/components/logical_xor.cpp b/qucs/components/logical_xor.cpp
index 5667a282..2a6d03d2 100644
--- a/qucs/components/logical_xor.cpp
+++ b/qucs/components/logical_xor.cpp
@@ -35,8 +35,8 @@ Logical_XOR::~Logical_XOR()
 Component* Logical_XOR::newOne()
 {
   Logical_XOR* p = new Logical_XOR();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
-  p->Props.getLast()->Value = Props.getLast()->Value;
+  p->Props.front()->Value = Props.front()->Value;
+  p->Props.back()->Value = Props.back()->Value;
   p->recreate(0);
   return p;
 }
diff --git a/qucs/components/mod_amp.cpp b/qucs/components/mod_amp.cpp
index 052139b8..f47449d7 100644
--- a/qucs/components/mod_amp.cpp
+++ b/qucs/components/mod_amp.cpp
@@ -60,7 +60,7 @@ mod_amp::mod_amp()
 Component * mod_amp::newOne()
 {
   mod_amp * p = new mod_amp();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/mosfet.cpp b/qucs/components/mosfet.cpp
index 8405b88d..ba1f9917 100644
--- a/qucs/components/mosfet.cpp
+++ b/qucs/components/mosfet.cpp
@@ -38,8 +38,8 @@ MOSFET::MOSFET()
 Component* MOSFET::newOne()
 {
   MOSFET* p = new MOSFET();
-  p->Props.first()->Value = Props.first()->Value;
-  p->Props.next()->Value = Props.next()->Value;
+  p->Props.at(0)->Value = Props.at(0)->Value;
+  p->Props.at(1)->Value = Props.at(1)->Value;
   p->recreate(0);
   return p;
 }
@@ -62,8 +62,8 @@ Element* MOSFET::info_p(QString& Name, char* &BitmapFile, bool getNewOne)
 
   if(getNewOne) {
     MOSFET* p = new MOSFET();
-    p->Props.first()->Value = "pfet";
-    p->Props.next()->Value = "-1.0 V";
+    p->Props.at(0)->Value = "pfet";
+    p->Props.at(1)->Value = "-1.0 V";
     p->recreate(0);
     return p;
   }
@@ -78,8 +78,7 @@ Element* MOSFET::info_depl(QString& Name, char* &BitmapFile, bool getNewOne)
 
   if(getNewOne) {
     MOSFET* p = new MOSFET();
-    p->Props.first();
-    p->Props.next()->Value = "-1.0 V";
+    p->Props.at(1)->Value = "-1.0 V";
     p->recreate(0);
     return p;
   }
@@ -110,8 +109,8 @@ void MOSFET::createSymbol()
     Lines.append(new qucs::Line( -1,  0, -6,  5,QPen(Qt::darkBlue,2)));
   }
 
-  if((Props.next()->Value.trimmed().at(0) == '-') ==
-     (Props.first()->Value == "nfet"))
+  if((Props.at(1)->Value.trimmed().at(0) == '-') ==
+     (Props.at(0)->Value == "nfet"))
     Lines.append(new qucs::Line(-10, -8,-10,  8,QPen(Qt::darkBlue,2)));
   else
     Lines.append(new qucs::Line(-10, -4,-10,  4,QPen(Qt::darkBlue,2)));
@@ -135,7 +134,7 @@ QString MOSFET::netlist()
   s += " "+Ports.at(2)->Connection->Name;  // connect substrate to source
 
   // output all properties
-  for(Property *p2 = Props.first(); p2 != 0; p2 = Props.next())
+  for(Property *p2 : Props)
     s += " "+p2->Name+"=\""+p2->Value+"\"";
 
   return s + '\n';
diff --git a/qucs/components/mosfet_sub.cpp b/qucs/components/mosfet_sub.cpp
index 2c794814..ab63091d 100644
--- a/qucs/components/mosfet_sub.cpp
+++ b/qucs/components/mosfet_sub.cpp
@@ -142,8 +142,8 @@ MOSFET_sub::MOSFET_sub()
 Component* MOSFET_sub::newOne()
 {
   MOSFET_sub* p = new MOSFET_sub();
-  p->Props.first()->Value = Props.first()->Value;
-  p->Props.next()->Value = Props.next()->Value;
+  p->Props.at(0)->Value = Props.at(0)->Value;
+  p->Props.at(1)->Value = Props.at(1)->Value;
   p->recreate(0);
   return p;
 }
@@ -225,8 +225,8 @@ Element* MOSFET_sub::info_p(QString& Name,
 
   if(getNewOne) {
     MOSFET_sub* p = new MOSFET_sub();
-    p->Props.first()->Value = "pfet";
-    p->Props.next()->Value = "-1.0 V";
+    p->Props.at(0)->Value = "pfet";
+    p->Props.at(1)->Value = "-1.0 V";
     p->recreate(0);
     return p;
   }
@@ -242,8 +242,7 @@ Element* MOSFET_sub::info_depl(QString& Name,
 
   if(getNewOne) {
     MOSFET_sub* p = new MOSFET_sub();
-    p->Props.first();
-    p->Props.next()->Value = "-1.0 V";
+    p->Props.at(1)->Value = "-1.0 V";
     p->recreate(0);
     return p;
   }
@@ -267,7 +266,7 @@ void MOSFET_sub::createSymbol()
 
   Lines.append(new qucs::Line( -4, 24,  4, 20,QPen(Qt::darkBlue,2)));
 
-  if(Props.first()->Value == "nfet") {
+  if(Props.at(0)->Value == "nfet") {
     Lines.append(new qucs::Line( -9,  0, -4, -5,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line( -9,  0, -4,  5,QPen(Qt::darkBlue,2)));
   }
@@ -276,7 +275,7 @@ void MOSFET_sub::createSymbol()
     Lines.append(new qucs::Line( -1,  0, -6,  5,QPen(Qt::darkBlue,2)));
   }
 
-  if((Props.next()->Value.trimmed().at(0) == '-') ==
+  if((Props.at(1)->Value.trimmed().at(0) == '-') ==
      (Props.first()->Value == "nfet"))
     Lines.append(new qucs::Line(-10, -8,-10,  8,QPen(Qt::darkBlue,2)));
   else
diff --git a/qucs/components/mscross.cpp b/qucs/components/mscross.cpp
index 999f275d..3149ccf4 100644
--- a/qucs/components/mscross.cpp
+++ b/qucs/components/mscross.cpp
@@ -91,7 +91,7 @@ void MScross::createSymbol()
   Lines.append(new qucs::Line(  8,-18,  8, -8,QPen(Qt::darkBlue,2)));
   Lines.append(new qucs::Line( -8,-18,  8,-18,QPen(Qt::darkBlue,2)));
 
-  if(Props.getLast()->Value.at(0) != 'n') {
+  if(Props.back()->Value.at(0) != 'n') {
     Texts.append(new Text(-26,  3, "1"));
     Texts.append(new Text(-10,-30, "2"));
     Texts.append(new Text( 21,-13, "3"));
diff --git a/qucs/components/mstee.cpp b/qucs/components/mstee.cpp
index 75dcd8d5..ccb384ac 100644
--- a/qucs/components/mstee.cpp
+++ b/qucs/components/mstee.cpp
@@ -96,7 +96,7 @@ void MStee::createSymbol()
   Lines.append(new qucs::Line(  8,  8,  8, 18,QPen(Qt::darkBlue,2)));
   Lines.append(new qucs::Line( -8, 18,  8, 18,QPen(Qt::darkBlue,2)));
 
-  if(Props.getLast()->Value.at(0) != 'n') {
+  if(Props.back()->Value.at(0) != 'n') {
     QString stmp = "1"; 
     int w = smallmetrics.boundingRect(stmp).width();
     int d = smallmetrics.descent();
diff --git a/qucs/components/msvia.cpp b/qucs/components/msvia.cpp
index b40d50af..bf6c44f2 100644
--- a/qucs/components/msvia.cpp
+++ b/qucs/components/msvia.cpp
@@ -80,7 +80,7 @@ QString MSvia::netlist()
   s += " " + Ports.first()->Connection->Name + " gnd";
 
   // output all properties
-  for(Property *p2 = Props.first(); p2 != 0; p2 = Props.next())
+  for(Property *p2 : Props)
     s += " "+p2->Name+"=\""+p2->Value+"\"";
 
   return s + '\n';
diff --git a/qucs/components/mutualx.cpp b/qucs/components/mutualx.cpp
index 43fe84d6..d29e06d2 100644
--- a/qucs/components/mutualx.cpp
+++ b/qucs/components/mutualx.cpp
@@ -153,15 +153,17 @@ void MutualX::createSymbol()
     int dCoils = abs(oldCoils - Num);          // how many coils were added/removed?
 
     if (oldCoils>Num) { // reduce coils number
-      for(int i = 0; i < dCoils; i++)
-        Props.remove(Num+1); // remove excess coils
+      for(int i = 0; i < dCoils; i++){
+        Props.removeAt(Num+1); // remove excess coils
+      }
+
       // remove only the no longer valid coupling coefficients, leave the
       //   ones related to existing coils untouched
       for(int i = 1,state=1; i < oldCoils; i++)
         for(int j = i+1; j <= oldCoils; j++,state++) {
             if ((i>Num)||(j>Num)) {
-                Props.remove(Num + state);
-                state--;
+              Props.removeAt(Num + state);
+              state--;
             }
         }
 
@@ -186,11 +188,12 @@ void MutualX::createSymbol()
   // in any case rewrite properties Name and Description
   // (when loading a component, added properties have a default name)
   // adjust coils names
-  Property * p1 = Props.at(1);
+  auto p1 = Props.begin();
+  ++p1;
   for(int i = 1; i <= Num; i++) {
-    p1->Name = "L"+QString::number(i);
-    p1->Description = QObject::tr("inductance of coil") + " " + QString::number(i);
-    p1 = Props.next();
+    (*p1)->Name = "L"+QString::number(i);
+    (*p1)->Description = QObject::tr("inductance of coil") + " " + QString::number(i);
+    p1++;
   }
   // adjust coupling coeffs names
   for(int i = 1,state=1; i < Num; i++) 
diff --git a/qucs/components/mux2to1.cpp b/qucs/components/mux2to1.cpp
index a750a074..21786435 100644
--- a/qucs/components/mux2to1.cpp
+++ b/qucs/components/mux2to1.cpp
@@ -40,7 +40,7 @@ mux2to1::mux2to1()
 Component * mux2to1::newOne()
 {
   mux2to1 * p = new mux2to1();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/mux4to1.cpp b/qucs/components/mux4to1.cpp
index b8bd3562..27aa1061 100644
--- a/qucs/components/mux4to1.cpp
+++ b/qucs/components/mux4to1.cpp
@@ -40,7 +40,7 @@ mux4to1::mux4to1()
 Component * mux4to1::newOne()
 {
   mux4to1 * p = new mux4to1();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/mux8to1.cpp b/qucs/components/mux8to1.cpp
index 7ff6a1e1..d71328fc 100644
--- a/qucs/components/mux8to1.cpp
+++ b/qucs/components/mux8to1.cpp
@@ -41,7 +41,7 @@ mux8to1::mux8to1()
 Component * mux8to1::newOne()
 {
   mux8to1 * p = new mux8to1();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/nigbt.cpp b/qucs/components/nigbt.cpp
index d74e9c1a..793e4108 100644
--- a/qucs/components/nigbt.cpp
+++ b/qucs/components/nigbt.cpp
@@ -81,7 +81,7 @@ nigbt::nigbt()
 Component * nigbt::newOne()
 {
   nigbt * p = new nigbt();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/opt_sim.cpp b/qucs/components/opt_sim.cpp
index 73b7f098..96ea6178 100644
--- a/qucs/components/opt_sim.cpp
+++ b/qucs/components/opt_sim.cpp
@@ -72,7 +72,7 @@ QString Optimize_Sim::netlist()
 // -----------------------------------------------------------
 bool Optimize_Sim::createASCOFiles()
 {
-  Property* pp;
+
   QFile afile(QucsSettings.tempFilesDir.filePath("asco_netlist.cfg"));
   if(afile.open(QIODevice::WriteOnly)) {
     QTextStream stream(&afile);
@@ -88,62 +88,62 @@ bool Optimize_Sim::createASCOFiles()
     stream << "#\n\n";
 
     stream << "#DE#\n";
-    pp = Props.at(1);
+
     QString val;
-    val = pp->Value.section('|',0,0);
+    val = Props.at(1)->Value.section('|',0,0);
     stream << "choice of method:" << val << "\n";
-    val = pp->Value.section('|',1,1);
+    val = Props.at(1)->Value.section('|',1,1);
     stream << "maximum no. of iterations:" << val << "\n";
-    val = pp->Value.section('|',2,2);
+    val = Props.at(1)->Value.section('|',2,2);
     stream << "Output refresh cycle:" << val << "\n";
-    val = pp->Value.section('|',3,3);
+    val = Props.at(1)->Value.section('|',3,3);
     stream << "No. of parents NP:" << val << "\n";
-    val= pp->Value.section('|',4,4);
+    val= Props.at(1)->Value.section('|',4,4);
     stream << "Constant F:" << val << "\n";
-    val = pp->Value.section('|',5,5);
+    val = Props.at(1)->Value.section('|',5,5);
     stream << "Crossing Over factor CR:" << val << "\n";
-    val = pp->Value.section('|',6,6);
+    val = Props.at(1)->Value.section('|',6,6);
     stream << "Seed for pseudo random number generator:" << val << "\n";
-    val = pp->Value.section('|',7,7);
+    val = Props.at(1)->Value.section('|',7,7);
     stream << "Minimum Cost Variance:" << val << "\n";
-    val = pp->Value.section('|',8,8);
+    val = Props.at(1)->Value.section('|',8,8);
     stream << "Cost objectives:" << val << "\n";
-    val = pp->Value.section('|',9,9);
+    val = Props.at(1)->Value.section('|',9,9);
     stream << "Cost constraints:" << val << "\n";
     stream << "#\n\n";
 
     stream << "# Parameters #\n";
-    int i=1;
-    for(pp = Props.at(2); pp != 0; pp = Props.next(), i++) {
-      if(pp->Name == "Var") {
-	stream << "Parameter " << i << ":";
-	val = pp->Value.section('|',0,0);
+
+    for(int i= 2; i < Props.size();i++) {
+      if(Props.at(i)->Name == "Var") {
+        stream << "Parameter " << i-1 << ":";
+        val = Props.at(i)->Value.section('|',0,0);
 	stream << "#" << val << "#" << ":";
-	val = pp->Value.section('|',2,2);
+        val = Props.at(i)->Value.section('|',2,2);
 	stream << val << ":";
-	val = pp->Value.section('|',3,3);
+        val = Props.at(i)->Value.section('|',3,3);
 	stream << val << ":";
-	val = pp->Value.section('|',4,4);
+        val = Props.at(i)->Value.section('|',4,4);
 	stream << val << ":";
-	val = pp->Value.section('|',5,5);
+        val = Props.at(i)->Value.section('|',5,5);
 	stream << val << ":";
-	val = pp->Value.section('|',1,1);
+        val = Props.at(i)->Value.section('|',1,1);
 	stream << ((val == "yes") ? "OPT" : "---") << "\n";
       }
     }
     stream << "#\n\n";
 
     stream << "# Measurements #\n";
-    for(pp = Props.at(2); pp != 0; pp = Props.next(), i++) {
-      if(pp->Name == "Goal") {
-	val = pp->Value.section('|',1,1);
+    for(int i= 2; i < Props.size();i++) {
+      if(Props.at(i)->Name == "Goal") {
+        val = Props.at(i)->Value.section('|',1,1);
 	QString Type, Value;
-	Value = pp->Value.section('|',2,2);
+        Value = Props.at(i)->Value.section('|',2,2);
 	if (val == "MIN" || val == "MAX" || val == "MON") {
 	  Value = "---";
 	}
 	Type = val;
-	val = pp->Value.section('|',0,0);
+        val = Props.at(i)->Value.section('|',0,0);
 	stream << val <<  ":"
 	       << "---" << ":"
 	       << Type << ":" << Value << "\n";
@@ -165,9 +165,9 @@ bool Optimize_Sim::createASCOFiles()
       return false;
   }      
 
-  for(pp = Props.at(2); pp != 0; pp = Props.next()) {
-    if(pp->Name == "Goal") {
-      QString VarName = pp->Value.section('|',0,0);
+  for(int i= 2; i < Props.size();i++) {
+    if(Props.at(i)->Name == "Goal") {
+      QString VarName = Props.at(i)->Value.section('|',0,0);
       QFile efile(ExtractDir.filePath(VarName));
       if(efile.open(QIODevice::WriteOnly)) {
     QTextStream stream(&efile);
@@ -195,11 +195,10 @@ bool Optimize_Sim::createASCOFiles()
  */
 bool Optimize_Sim::createASCOnetlist()
 {
-  Property* pp;
   QStringList vars;
-  for(pp = Props.at(2); pp != 0; pp = Props.next()) {
-    if(pp->Name == "Var") {
-      vars += pp->Value.section('|',0,0);
+  for(int i= 2; i < Props.size();i++) {
+    if(Props.at(i)->Name == "Var") {
+      vars += Props.at(i)->Value.section('|',0,0);
     }
   }
 
@@ -245,11 +244,10 @@ bool Optimize_Sim::createASCOnetlist()
 bool Optimize_Sim::loadASCOout()
 {
   bool changed = false;
-  Property* pp;
   QStringList vars;
-  for(pp = Props.at(2); pp != 0; pp = Props.next()) {
-    if(pp->Name == "Var") {
-      vars += pp->Value.section('|',0,0);
+  for(int i= 2; i < Props.size();i++) {
+    if(Props.at(i)->Name == "Var") {
+      vars += Props.at(i)->Value.section('|',0,0);
     }
   }
 
@@ -267,21 +265,21 @@ bool Optimize_Sim::loadASCOout()
     QString Name = *it;
     Name = Name.trimmed();
     if(vars.contains(Name)) {
-      for(pp = Props.at(2); pp != 0; pp = Props.next()) {
-	if(pp->Name == "Var") {
+      for(int i= 2; i < Props.size();i++) {
+        if(Props.at(i)->Name == "Var") {
 	  QString val[6];
-	  val[0] = pp->Value.section('|',0,0); // variable name
+          val[0] = Props.at(i)->Value.section('|',0,0); // variable name
 	  if(val[0]==Name) {
-	    val[1] = pp->Value.section('|',1,1);
-	    val[2] = pp->Value.section('|',2,2);
-	    val[3] = pp->Value.section('|',3,3);
-	    val[4] = pp->Value.section('|',4,4);
-	    val[5] = pp->Value.section('|',5,5);
+            val[1] = Props.at(i)->Value.section('|',1,1);
+            val[2] = Props.at(i)->Value.section('|',2,2);
+            val[3] = Props.at(i)->Value.section('|',3,3);
+            val[4] = Props.at(i)->Value.section('|',4,4);
+            val[5] = Props.at(i)->Value.section('|',5,5);
 	    ++it; // field after variable name is its value
 	    QString Value = *it;
 	    Value = Value.trimmed();
 	    val[2] = Value;
-	    pp->Value = val[0] + "|" + val[1] + "|" + val[2] + "|" +
+            Props.at(i)->Value = val[0] + "|" + val[1] + "|" + val[2] + "|" +
 	      val[3] + "|" + val[4] + "|" + val[5];
 	    changed = true;
 	    break;
diff --git a/qucs/components/optimizedialog.cpp b/qucs/components/optimizedialog.cpp
index f6f8a6ae..e8a52cce 100644
--- a/qucs/components/optimizedialog.cpp
+++ b/qucs/components/optimizedialog.cpp
@@ -352,37 +352,39 @@ OptimizeDialog::OptimizeDialog(Optimize_Sim *c_, Schematic *d_)
       if(pc->Model[0] == '.' && pc->Model != ".Opt")
         SimEdit->insertItem(SimEdit->count(), pc->Name);
 
-  Property *pp;
-  pp = Comp->Props.at(0);
-  if(!pp->Value.isEmpty()) {
+  auto p0 = Comp->Props.at(0);
+  if(!p0->Value.isEmpty()) {
     // set selected simulation in combo box to the currently used one
-    int i = SimEdit->findText(pp->Value);
+    int i = SimEdit->findText(p0->Value);
     if (i != -1) // current simulation is in the available simulations list (normal case)
       SimEdit->setCurrentIndex(i);
     else  // current simulation not in the available simulations list
-      SimEdit->setEditText(pp->Value);
+      SimEdit->setEditText(p0->Value);
   }
 
-  pp = Comp->Props.at(1);
-  if(!pp->Value.isEmpty()) {
-    MethodCombo->setCurrentIndex(pp->Value.section('|',0,0).toInt()-1);
-    IterEdit->setText(pp->Value.section('|',1,1));
-    RefreshEdit->setText(pp->Value.section('|',2,2));
-    ParentsEdit->setText(pp->Value.section('|',3,3));
-    ConstEdit->setText(pp->Value.section('|',4,4));
-    CrossEdit->setText(pp->Value.section('|',5,5));
-    SeedEdit->setText(pp->Value.section('|',6,6));
-    CostVarEdit->setText(pp->Value.section('|',7,7));
-    CostObjEdit->setText(pp->Value.section('|',8,8));
-    CostConEdit->setText(pp->Value.section('|',9,9));
+  auto p1 = Comp->Props.at(1);
+  if(!p1->Value.isEmpty()) {
+    MethodCombo->setCurrentIndex(p1->Value.section('|',0,0).toInt()-1);
+    IterEdit->setText(p1->Value.section('|',1,1));
+    RefreshEdit->setText(p1->Value.section('|',2,2));
+    ParentsEdit->setText(p1->Value.section('|',3,3));
+    ConstEdit->setText(p1->Value.section('|',4,4));
+    CrossEdit->setText(p1->Value.section('|',5,5));
+    SeedEdit->setText(p1->Value.section('|',6,6));
+    CostVarEdit->setText(p1->Value.section('|',7,7));
+    CostObjEdit->setText(p1->Value.section('|',8,8));
+    CostConEdit->setText(p1->Value.section('|',9,9));
   }
 
   NameEdit->setText(Comp->Name);
 
   QTableWidgetItem *item;
-  for(pp = Comp->Props.at(2); pp != 0; pp = Comp->Props.next()) {
-    if(pp->Name == "Var") {
-      QStringList ValueSplit = pp->Value.split("|");
+  auto pp = Comp->Props.begin();
+  ++pp;
+  ++pp;
+  for(;pp!=Comp->Props.end();++pp) {
+    if((*pp)->Name == "Var") {
+      QStringList ValueSplit = (*pp)->Value.split("|");
       int row = VarTable->rowCount();
       VarTable->insertRow(row);
       // Name
@@ -434,8 +436,8 @@ OptimizeDialog::OptimizeDialog(Optimize_Sim *c_, Schematic *d_)
       item->setFlags(item->flags() & ~Qt::ItemIsEditable);
       VarTable->setItem(row, 5, item);
     }
-    if(pp->Name == "Goal") {
-      QStringList GoalSplit = pp->Value.split("|");
+    if((*pp)->Name == "Goal") {
+      QStringList GoalSplit = (*pp)->Value.split("|");
       int row = GoalTable->rowCount();
       GoalTable->insertRow(row);
 
@@ -757,7 +759,9 @@ void OptimizeDialog::slotApply()
     changed = true;
   }
 
-  Property *pp = Comp->Props.at(2);
+  auto pp = Comp->Props.begin();
+  ++pp;
+  ++pp;
   int row;
   // apply all the new property values in the TableWidget
   for (row = 0; row < VarTable->rowCount(); ++row) {
@@ -793,21 +797,22 @@ void OptimizeDialog::slotApply()
     }
     Prop = propList.join("|");
 
-    if(pp) {
-      if(pp->Name != "Var") {
-        pp->Name = "Var";
+    if(pp != Comp->Props.end()) {
+      if((*pp)->Name != "Var") {
+        (*pp)->Name = "Var";
         changed = true;
       }
-      if(pp->Value != Prop) {
-        pp->Value = Prop;
+      if((*pp)->Value != Prop) {
+        (*pp)->Value = Prop;
         changed = true;
       }
     }
     else {
       Comp->Props.append(new Property("Var", Prop, false, ""));
+      pp = Comp->Props.end()-1;
       changed = true;
     }
-    pp = Comp->Props.next();
+    pp++;
   }
 
   for (row = 0; row < GoalTable->rowCount(); ++row) {
@@ -830,29 +835,27 @@ void OptimizeDialog::slotApply()
     propList << GoalTable->item(row, 2)->text();
     Prop = propList.join("|");
 
-    if(pp) {
-      if(pp->Name != "Goal") {
-        pp->Name = "Goal";
+    if(pp != Comp->Props.end()) {
+      if((*pp)->Name != "Goal") {
+        (*pp)->Name = "Goal";
         changed = true;
       }
-      if(pp->Value != Prop) {
-        pp->Value = Prop;
+      if((*pp)->Value != Prop) {
+        (*pp)->Value = Prop;
         changed = true;
       }
     }
     else {
       Comp->Props.append(new Property("Goal", Prop, false, ""));
+      pp = Comp->Props.end()-1;
       changed = true;
     }
-    pp = Comp->Props.next();
+    pp++;
   }
 
   // if more properties than in ListView -> delete the rest
-  if(pp) {
-    pp = Comp->Props.prev();
-    Comp->Props.last();
-    while(pp != Comp->Props.current())
-      Comp->Props.remove();
+  if(pp != Comp->Props.end()) {
+    Comp->Props.erase(pp, Comp->Props.end());
     changed = true;
   }
 
@@ -876,10 +879,9 @@ void OptimizeDialog::slotCreateEqn()
               //<Model Name ShowName cx cy tx ty mirroredX rotate
               "<Eqn OptValues 1 0 0 -28 15 0 0 ";
 
- Property *pp;
- for(pp = Comp->Props.at(2); pp != 0; pp = Comp->Props.next()) {
-   if(pp->Name == "Var") { // property is an optimization variable
-      QStringList ValueSplit = pp->Value.split("|");
+  for(int i = 2;i<Comp->Props.size();i++) {
+    if(Comp->Props.at(i)->Name == "Var") { // property is an optimization variable
+      QStringList ValueSplit = Comp->Props.at(i)->Value.split("|");
       // "Name" = "initial (current) value"
       s += "\"" + ValueSplit.at(0) + "=" + ValueSplit.at(2) + "\" 1 ";
    }
@@ -920,11 +922,10 @@ void OptimizeDialog::slotSetPrecision(const QPoint& pos)
     numPrec = i;
     // update the shown values according to the new precision
     int row = 0;
-    Property *pp;
     QTableWidgetItem *item;
-    for(pp = Comp->Props.at(2); pp != 0; pp = Comp->Props.next()) {
-      if(pp->Name == "Var") {
-	QStringList ValueSplit = pp->Value.split("|");
+    for(int i = 2; i< Comp->Props.size(); i++) {
+      if(Comp->Props.at(i)->Name == "Var") {
+        QStringList ValueSplit = Comp->Props.at(i)->Value.split("|");
 	// 'initial' column
 	item = VarTable->item(row++, 2);
 	item->setText(QString::number(ValueSplit.at(2).toDouble(), 'g', numPrec));
diff --git a/qucs/components/pad2bit.cpp b/qucs/components/pad2bit.cpp
index 754b6f1f..c8351971 100644
--- a/qucs/components/pad2bit.cpp
+++ b/qucs/components/pad2bit.cpp
@@ -29,7 +29,7 @@ pad2bit::pad2bit()
 Component * pad2bit::newOne()
 {
   pad2bit * p = new pad2bit();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/pad3bit.cpp b/qucs/components/pad3bit.cpp
index d6488d54..e274c075 100644
--- a/qucs/components/pad3bit.cpp
+++ b/qucs/components/pad3bit.cpp
@@ -29,7 +29,7 @@ pad3bit::pad3bit()
 Component * pad3bit::newOne()
 {
   pad3bit * p = new pad3bit();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/pad4bit.cpp b/qucs/components/pad4bit.cpp
index f6bf4944..22320291 100644
--- a/qucs/components/pad4bit.cpp
+++ b/qucs/components/pad4bit.cpp
@@ -29,7 +29,7 @@ pad4bit::pad4bit()
 Component * pad4bit::newOne()
 {
   pad4bit * p = new pad4bit();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/param_sweep.cpp b/qucs/components/param_sweep.cpp
index 8ff292ca..ee614231 100644
--- a/qucs/components/param_sweep.cpp
+++ b/qucs/components/param_sweep.cpp
@@ -64,22 +64,18 @@ Element* Param_Sweep::info(QString& Name, char* &BitmapFile, bool getNewOne)
 
 void Param_Sweep::recreate(Schematic*)
 {
-  Property *pp = Props.at(1);
-  Props.next();
-  if((pp->Value == "list") || (pp->Value == "const")) {
+  if((Props.at(1)->Value == "list") || (Props.at(1)->Value == "const")) {
     // Call them "Symbol" to omit them in the netlist.
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    Props.next()->Name = "Values";
+    Props.at(3)->Name = "Symbol";
+    Props.at(3)->display = false;
+    Props.at(4)->Name = "Symbol";
+    Props.at(4)->display = false;
+    Props.at(5)->Name = "Values";
   }
   else {
-    Props.next()->Name = "Start";
-    Props.next()->Name = "Stop";
-    Props.next()->Name = "Points";
+    Props.at(3)->Name = "Start";
+    Props.at(4)->Name = "Stop";
+    Props.at(5)->Name = "Points";
   }
 }
 
diff --git a/qucs/components/photodiode.cpp b/qucs/components/photodiode.cpp
index fc7d523e..01feb704 100644
--- a/qucs/components/photodiode.cpp
+++ b/qucs/components/photodiode.cpp
@@ -86,7 +86,7 @@ photodiode::photodiode()
 Component * photodiode::newOne()
 {
   photodiode * p = new photodiode();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/phototransistor.cpp b/qucs/components/phototransistor.cpp
index 8bec0bcd..7441c434 100644
--- a/qucs/components/phototransistor.cpp
+++ b/qucs/components/phototransistor.cpp
@@ -102,7 +102,7 @@ phototransistor::phototransistor()
 Component * phototransistor::newOne()
 {
   phototransistor * p = new phototransistor();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/potentiometer.cpp b/qucs/components/potentiometer.cpp
index 22b8f8f3..60f7aa4c 100644
--- a/qucs/components/potentiometer.cpp
+++ b/qucs/components/potentiometer.cpp
@@ -59,7 +59,7 @@ potentiometer::potentiometer()
 Component * potentiometer::newOne()
 {
   potentiometer * p = new potentiometer();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/resistor.cpp b/qucs/components/resistor.cpp
index 82d228d2..20549ea4 100644
--- a/qucs/components/resistor.cpp
+++ b/qucs/components/resistor.cpp
@@ -37,7 +37,7 @@ Resistor::Resistor(bool european)
   // this must be the last property in the list !!!
   Props.append(new Property("Symbol", "european", false,
         QObject::tr("schematic symbol")+" [european, US]"));
-  if(!european)  Props.getLast()->Value = "US";
+  if(!european)  Props.back()->Value = "US";
 
   createSymbol();
   tx = x1+4;
@@ -50,7 +50,7 @@ Resistor::Resistor(bool european)
 // -------------------------------------------------------
 Component* Resistor::newOne()
 {
-  return new Resistor(Props.getLast()->Value != "US");
+  return new Resistor(Props.back()->Value != "US");
 }
 
 QString Resistor::spice_netlist(bool )
@@ -100,7 +100,7 @@ QString Resistor::va_code()
 // -------------------------------------------------------
 void Resistor::createSymbol()
 {
-  if(Props.getLast()->Value != "US") {
+  if(Props.back()->Value != "US") {
     Lines.append(new qucs::Line(-18, -9, 18, -9,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line( 18, -9, 18,  9,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line( 18,  9,-18,  9,QPen(Qt::darkBlue,2)));
diff --git a/qucs/components/rfedd.cpp b/qucs/components/rfedd.cpp
index 5e686f4d..bfe3d9d6 100644
--- a/qucs/components/rfedd.cpp
+++ b/qucs/components/rfedd.cpp
@@ -89,19 +89,17 @@ QString RFedd::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output all properties
-  Property *p2;
-  p2 = Props.at(0);
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
-  p = p2->Value;
-  p2 = Props.at(2);
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
-  p2 = Props.at(3);
-  while(p2) {
-    n = p2->Name.mid(1);
-    s += " "+p2->Name+"=\""+Name+"."+p+n+"\"";
-    e += "  Eqn:Eqn"+Name+p2->Name+" "+
-      Name+"."+p+n+"=\""+p2->Value+"\" Export=\"no\"\n";
-    p2 = Props.next();
+
+         // output all properties
+  s += " "+Props.at(0)->Name+"=\""+Props.at(0)->Value+"\"";
+  p = Props.at(0)->Value;
+  s += " "+Props.at(2)->Name+"=\""+Props.at(2)->Value+"\"";
+
+  for (int i = 3; i < int(Props.size()); ++i) {
+    n = Props.at(i)->Name.mid(1);
+    s += " "+Props.at(i)->Name+"=\""+Name+"."+p+n+"\"";
+    e += "  Eqn:Eqn"+Name+Props.at(i)->Name+" "+
+         Name+"."+p+n+"=\""+Props.at(i)->Value+"\" Export=\"no\"\n";
   }
 
   return s+e;
diff --git a/qucs/components/rfedd2p.cpp b/qucs/components/rfedd2p.cpp
index ecd72367..b7132a1e 100644
--- a/qucs/components/rfedd2p.cpp
+++ b/qucs/components/rfedd2p.cpp
@@ -87,19 +87,15 @@ QString RFedd2P::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output all properties
-  Property *p2;
-  p2 = Props.at(0);
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
-  p = p2->Value;
-  p2 = Props.at(1);
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
-  p2 = Props.at(2);
-  while(p2) {
-    n = p2->Name.mid(1);
-    s += " "+p2->Name+"=\""+Name+"."+p+n+"\"";
-    e += "  Eqn:Eqn"+Name+p2->Name+" "+
-      Name+"."+p+n+"=\""+p2->Value+"\" Export=\"no\"\n";
-    p2 = Props.next();
+  // output all properties
+  s += " "+Props.at(0)->Name+"=\""+Props.at(0)->Value+"\"";
+  p = Props.at(0)->Value;
+  s += " "+Props.at(1)->Name+"=\""+Props.at(1)->Value+"\"";
+  for (int i = 2; i < int(Props.size()); ++i) {
+    n = Props.at(i)->Name.mid(1);
+    s += " "+Props.at(i)->Name+"=\""+Name+"."+p+n+"\"";
+    e += "  Eqn:Eqn"+Name+Props.at(i)->Name+" "+
+         Name+"."+p+n+"=\""+Props.at(i)->Value+"\" Export=\"no\"\n";
   }
 
   return s+e;
diff --git a/qucs/components/sp_sim.cpp b/qucs/components/sp_sim.cpp
index 98b14c9b..c14e4fa8 100644
--- a/qucs/components/sp_sim.cpp
+++ b/qucs/components/sp_sim.cpp
@@ -73,21 +73,18 @@ Element* SP_Sim::info(QString& Name, char* &BitmapFile, bool getNewOne)
 
 void SP_Sim::recreate(Schematic*)
 {
-  Property *pp = Props.first();
-  if((pp->Value == "list") || (pp->Value == "const")) {
+  if((Props.at(0)->Value == "list") || (Props.at(0)->Value == "const")) {
     // Call them "Symbol" to omit them in the netlist.
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    Props.next()->Name = "Values";
+    Props.at(1)->Name = "Symbol";
+    Props.at(1)->display = false;
+    Props.at(2)->Name = "Symbol";
+    Props.at(2)->display = false;
+    Props.at(3)->Name = "Values";
   }
   else {
-    Props.next()->Name = "Start";
-    Props.next()->Name = "Stop";
-    Props.next()->Name = "Points";
+    Props.at(1)->Name = "Start";
+    Props.at(2)->Name = "Stop";
+    Props.at(3)->Name = "Points";
   }
 }
 
diff --git a/qucs/components/sparamfile.cpp b/qucs/components/sparamfile.cpp
index 3fca3aa4..809fd6f6 100644
--- a/qucs/components/sparamfile.cpp
+++ b/qucs/components/sparamfile.cpp
@@ -53,7 +53,7 @@ SParamFile::SParamFile()
 Component* SParamFile::newOne()
 {
   SParamFile* p = new SParamFile();
-  p->Props.getLast()->Value = Props.getLast()->Value;
+  p->Props.back()->Value = Props.back()->Value;
   p->recreate(0);
   return p;
 }
@@ -66,8 +66,8 @@ Element* SParamFile::info(QString& Name, char* &BitmapFile, bool getNewOne)
 
   if(getNewOne) {
     SParamFile* p = new SParamFile();
-    p->Props.getFirst()->Value = "test.s3p";
-    p->Props.getLast()->Value = "3";
+    p->Props.front()->Value = "test.s3p";
+    p->Props.back()->Value = "3";
     p->recreate(0);
     return p;
   }
@@ -92,8 +92,8 @@ Element* SParamFile::info2(QString& Name, char* &BitmapFile, bool getNewOne)
 
   if(getNewOne) {
     SParamFile* p = new SParamFile();
-    p->Props.getFirst()->Value = "test.s2p";
-    p->Props.getLast()->Value = "2";
+    p->Props.front()->Value = "test.s2p";
+    p->Props.back()->Value = "2";
     p->recreate(0);
     return p;
   }
@@ -103,10 +103,10 @@ Element* SParamFile::info2(QString& Name, char* &BitmapFile, bool getNewOne)
 // -------------------------------------------------------
 QString SParamFile::getSubcircuitFile()
 {
-  return misc::properAbsFileName(Props.getFirst()->Value, containingSchematic);
+  return misc::properAbsFileName(Props.front()->Value, containingSchematic);
 
   // construct full filename
-  QString FileName = Props.getFirst()->Value;
+  QString FileName = Props.front()->Value;
   return misc::properAbsFileName(FileName);
 }
 
@@ -120,20 +120,16 @@ QString SParamFile::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output all properties
-  Property *p2 = Props.first();
-  s += " "+p2->Name+"=\"{"+getSubcircuitFile()+"}\"";
+  s += " "+Props.at(0)->Name+"=\"{"+getSubcircuitFile()+"}\"";
 
   // data type
-  p2 = Props.next();
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
+  s += " "+Props.at(1)->Name+"=\""+Props.at(1)->Value+"\"";
 
   // interpolator type
-  p2 = Props.next();
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
+  s += " "+Props.at(2)->Name+"=\""+Props.at(2)->Value+"\"";
 
   // DC property
-  p2 = Props.next();
-  s += " "+p2->Name+"=\""+p2->Value+"\"\n";
+  s += " "+Props.at(3)->Name+"=\""+Props.at(3)->Value+"\"\n";
 
   return s;
 }
@@ -150,7 +146,7 @@ void SParamFile::createSymbol()
   QString stmp;
 
   int w, PortDistance = 60;
-  int Num = Props.getLast()->Value.toInt();
+  int Num = Props.back()->Value.toInt();
 
   // adjust number of ports
   if(Num < 1) Num = 1;
@@ -158,7 +154,7 @@ void SParamFile::createSymbol()
     PortDistance = 20;
     if(Num > 40) Num = 40;
   }
-  Props.getLast()->Value = QString::number(Num);
+  Props.back()->Value = QString::number(Num);
 
   // draw symbol outline
   int h = (PortDistance/2)*((Num-1)/2) + 15;
diff --git a/qucs/components/spicedialog.cpp b/qucs/components/spicedialog.cpp
index f25240e3..f9a25390 100644
--- a/qucs/components/spicedialog.cpp
+++ b/qucs/components/spicedialog.cpp
@@ -157,7 +157,7 @@ SpiceDialog::SpiceDialog(QucsApp* App_, SpiceFile *c, Schematic *d)
   changed = false;
 
   // insert all properties into the ListBox
-  Property *pp = Comp->Props.first();
+  auto pp = Comp->Props.at(0);
   FileEdit->setText(pp->Value);
   FileCheck->setChecked(pp->display);
   SimCheck->setChecked(Comp->Props.at(2)->Value == "yes");
@@ -226,15 +226,15 @@ void SpiceDialog::slotButtApply()
   }
 
   // apply all the new property values
-  Property *pp = Comp->Props.first();
-  if(pp->Value != FileEdit->text())
+  auto pp = Comp->Props.begin();
+  if((*pp)->Value != FileEdit->text())
   {
-    pp->Value = FileEdit->text();
+    (*pp)->Value = FileEdit->text();
     changed = true;
   }
-  if(pp->display != FileCheck->isChecked())
+  if((*pp)->display != FileCheck->isChecked())
   {
-    pp->display = FileCheck->isChecked();
+    (*pp)->display = FileCheck->isChecked();
     changed = true;
   }
 
@@ -246,26 +246,26 @@ void SpiceDialog::slotButtApply()
     }
     tmp += "_net" + PortsList->item(i)->text();   // chosen ports
   }
-  pp = Comp->Props.next();
-  if(pp->Value != tmp)
+  pp++;
+  if((*pp)->Value != tmp)
   {
-    pp->Value = tmp;
+    (*pp)->Value = tmp;
     changed = true;
   }
-  pp = Comp->Props.next();
-  if((pp->Value=="yes") != SimCheck->isChecked())
+  pp++;
+  if(((*pp)->Value=="yes") != SimCheck->isChecked())
   {
-    pp->Value = ((SimCheck->isChecked())? "yes" : "no");
+    (*pp)->Value = ((SimCheck->isChecked())? "yes" : "no");
     changed = true;
   }
-  if(pp->Value != "yes") {
+  if((*pp)->Value != "yes") {
     Comp->withSim = false;
   }
 
-  pp = Comp->Props.next();
-  if(pp->Value != PrepCombo->currentText())
+  pp++;
+  if((*pp)->Value != PrepCombo->currentText())
   {
-    pp->Value = PrepCombo->currentText();
+    (*pp)->Value = PrepCombo->currentText();
     changed = true;
   }
 
diff --git a/qucs/components/spicefile.cpp b/qucs/components/spicefile.cpp
index af2a61a9..6a163b06 100644
--- a/qucs/components/spicefile.cpp
+++ b/qucs/components/spicefile.cpp
@@ -168,7 +168,7 @@ QString SpiceFile::netlist()
 // -------------------------------------------------------
 QString SpiceFile::getSubcircuitFile()
 {
-  return misc::properAbsFileName(Props.getFirst()->Value, containingSchematic);
+  return misc::properAbsFileName(Props.front()->Value, containingSchematic);
 }
 
 // -------------------------------------------------------------------------
diff --git a/qucs/components/subcircuit.cpp b/qucs/components/subcircuit.cpp
index 93c78a55..ca9beae9 100644
--- a/qucs/components/subcircuit.cpp
+++ b/qucs/components/subcircuit.cpp
@@ -16,27 +16,24 @@
  ***************************************************************************/
 
 #include "subcircuit.h"
-#include "schematic.h"
+#include "extsimkernels/spicecompat.h"
 #include "main.h"
 #include "misc.h"
-#include "extsimkernels/spicecompat.h"
+#include "schematic.h"
 
-#include <QTextStream>
 #include <QFileInfo>
 #include <QMutex>
+#include <QTextStream>
 
-
-
-Subcircuit::Subcircuit()
-{
-  Type = isComponent;   // both analog and digital
+Subcircuit::Subcircuit() {
+  Type = isComponent; // both analog and digital
   Description = QObject::tr("subcircuit");
 
   Props.append(new Property("File", "", false,
-		QObject::tr("name of qucs schematic file")));
+                            QObject::tr("name of qucs schematic file")));
 
   Model = "Sub";
-  Name  = "SUB";
+  Name = "SUB";
   SpiceModel = "X";
 
   // Do NOT call createSymbol() here. But create port to let it rotate.
@@ -44,23 +41,21 @@ Subcircuit::Subcircuit()
 }
 
 // ---------------------------------------------------------------------
-Component* Subcircuit::newOne()
-{
+Component *Subcircuit::newOne() {
   Subcircuit *p = new Subcircuit();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0);
   return p;
 }
 
 // -------------------------------------------------------
-Element* Subcircuit::info(QString& Name, char* &BitmapFile, bool getNewOne)
-{
+Element *Subcircuit::info(QString &Name, char *&BitmapFile, bool getNewOne) {
   Name = QObject::tr("Subcircuit");
-  BitmapFile = (char *) "subcircuit";
+  BitmapFile = (char *)"subcircuit";
 
-  if(getNewOne) {
+  if (getNewOne) {
     Subcircuit *p = new Subcircuit();
-    p->recreate(0);   // createSymbol() is NOT called in constructor !!!
+    p->recreate(0); // createSymbol() is NOT called in constructor !!!
     return p;
   }
   return 0;
@@ -69,75 +64,77 @@ Element* Subcircuit::info(QString& Name, char* &BitmapFile, bool getNewOne)
 // ---------------------------------------------------------------------
 // Makes the schematic symbol subcircuit with the correct number
 // of ports.
-void Subcircuit::createSymbol()
-{
+void Subcircuit::createSymbol() {
   int No;
-  QString FileName(Props.getFirst()->Value);
+  QString FileName(Props.front()->Value);
   FileName = getSubcircuitFile();
 
   tx = INT_MIN;
   ty = INT_MIN;
-  if(loadSymbol(FileName) > 0) {  // try to load subcircuit symbol
-    if(tx == INT_MIN)  tx = x1+4;
-    if(ty == INT_MIN)  ty = y2+4;
+  if (loadSymbol(FileName) > 0) { // try to load subcircuit symbol
+    if (tx == INT_MIN)
+      tx = x1 + 4;
+    if (ty == INT_MIN)
+      ty = y2 + 4;
     // remove unused ports
     QMutableListIterator<Port *> ip(Ports);
     Port *pp;
     while (ip.hasNext()) {
       pp = ip.next();
-      if(!pp->avail) {
-          pp = ip.peekNext();
-          ip.remove();
+      if (!pp->avail) {
+        pp = ip.peekNext();
+        ip.remove();
       }
     }
-  }
-  else {
+  } else {
     No = Schematic::testFile(FileName);
-    if(No < 0)  No = 0;
+    if (No < 0)
+      No = 0;
 
     Ports.clear();
-    remakeSymbol(No);  // no symbol was found -> create standard symbol
+    remakeSymbol(No); // no symbol was found -> create standard symbol
   }
 }
 
 // ---------------------------------------------------------------------
-void Subcircuit::remakeSymbol(int No)
-{
-  int h = 30*((No-1)/2) + 15;
-  Lines.append(new qucs::Line(-15, -h, 15, -h,QPen(Qt::darkBlue,2)));
-  Lines.append(new qucs::Line( 15, -h, 15,  h,QPen(Qt::darkBlue,2)));
-  Lines.append(new qucs::Line(-15,  h, 15,  h,QPen(Qt::darkBlue,2)));
-  Lines.append(new qucs::Line(-15, -h,-15,  h,QPen(Qt::darkBlue,2)));
-  Texts.append(new Text(-10, -6,"sub"));
-
-  int i=0, y = 15-h;
-  while(i<No) {
+void Subcircuit::remakeSymbol(int No) {
+  int h = 30 * ((No - 1) / 2) + 15;
+  Lines.append(new qucs::Line(-15, -h, 15, -h, QPen(Qt::darkBlue, 2)));
+  Lines.append(new qucs::Line(15, -h, 15, h, QPen(Qt::darkBlue, 2)));
+  Lines.append(new qucs::Line(-15, h, 15, h, QPen(Qt::darkBlue, 2)));
+  Lines.append(new qucs::Line(-15, -h, -15, h, QPen(Qt::darkBlue, 2)));
+  Texts.append(new Text(-10, -6, "sub"));
+
+  int i = 0, y = 15 - h;
+  while (i < No) {
     i++;
-    Lines.append(new qucs::Line(-30,  y,-15,  y,QPen(Qt::darkBlue,2)));
-    Ports.append(new Port(-30,  y));
-    Texts.append(new Text(-25,y-14,QString::number(i)));
+    Lines.append(new qucs::Line(-30, y, -15, y, QPen(Qt::darkBlue, 2)));
+    Ports.append(new Port(-30, y));
+    Texts.append(new Text(-25, y - 14, QString::number(i)));
 
-    if(i == No) break;
+    if (i == No)
+      break;
     i++;
-    Lines.append(new qucs::Line( 15,  y, 30,  y,QPen(Qt::darkBlue,2)));
-    Ports.append(new Port( 30,  y));
-    Texts.append(new Text( 19,y-14,QString::number(i)));
+    Lines.append(new qucs::Line(15, y, 30, y, QPen(Qt::darkBlue, 2)));
+    Ports.append(new Port(30, y));
+    Texts.append(new Text(19, y - 14, QString::number(i)));
     y += 60;
   }
 
-  x1 = -30; y1 = -h-2;
-  x2 =  30; y2 =  h+2;
-  tx = x1+4;
-  ty = y2+4;
+  x1 = -30;
+  y1 = -h - 2;
+  x2 = 30;
+  y2 = h + 2;
+  tx = x1 + 4;
+  ty = y2 + 4;
 }
 
 // ---------------------------------------------------------------------
 // Loads the symbol for the subcircuit from the schematic file and
 // returns the number of painting elements.
-int Subcircuit::loadSymbol(const QString& DocName)
-{
+int Subcircuit::loadSymbol(const QString &DocName) {
   QFile file(DocName);
-  if(!file.open(QIODevice::ReadOnly))
+  if (!file.open(QIODevice::ReadOnly))
     return -1;
 
   QString Line;
@@ -149,107 +146,110 @@ int Subcircuit::loadSymbol(const QString& DocName)
   file.close();
   QTextStream stream(&FileString, QIODevice::ReadOnly);
 
-
   // read header **************************
   do {
-    if(stream.atEnd()) return -2;
+    if (stream.atEnd())
+      return -2;
     Line = stream.readLine();
     Line = Line.trimmed();
-  } while(Line.isEmpty());
+  } while (Line.isEmpty());
 
-  if(Line.left(16) != "<Qucs Schematic ")  // wrong file type ?
+  if (Line.left(16) != "<Qucs Schematic ") // wrong file type ?
     return -3;
 
-  Line = Line.mid(16, Line.length()-17);
+  Line = Line.mid(16, Line.length() - 17);
   VersionTriplet SymbolVersion = VersionTriplet(Line);
-  if (SymbolVersion > QucsVersion) {// wrong version number ?
-      if (!QucsSettings.IgnoreFutureVersion) {
-          return -4;
-      }
+  if (SymbolVersion > QucsVersion) { // wrong version number ?
+    if (!QucsSettings.IgnoreFutureVersion) {
+      return -4;
+    }
   }
 
   // read content *************************
-  while(!stream.atEnd()) {
+  while (!stream.atEnd()) {
     Line = stream.readLine();
-    if(Line == "<Symbol>") break;
+    if (Line == "<Symbol>")
+      break;
   }
 
   x1 = y1 = INT_MAX;
   x2 = y2 = INT_MIN;
 
-  int z=0, Result;
-  while(!stream.atEnd()) {
+  int z = 0, Result;
+  while (!stream.atEnd()) {
     Line = stream.readLine();
-    if(Line == "</Symbol>") {
-      x1 -= 4;   // enlarge component boundings a little
+    if (Line == "</Symbol>") {
+      x1 -= 4; // enlarge component boundings a little
       x2 += 4;
       y1 -= 4;
       y2 += 4;
-      return z;      // return number of ports
+      return z; // return number of ports
     }
 
     Line = Line.trimmed();
-    if(Line.at(0) != '<') return -5;
-    if(Line.at(Line.length()-1) != '>') return -6;
-    Line = Line.mid(1, Line.length()-2); // cut off start and end character
+    if (Line.at(0) != '<')
+      return -5;
+    if (Line.at(Line.length() - 1) != '>')
+      return -6;
+    Line = Line.mid(1, Line.length() - 2); // cut off start and end character
     Result = analyseLine(Line, 1);
-    if(Result < 0) return -7;   // line format error
+    if (Result < 0)
+      return -7; // line format error
     z += Result;
   }
 
-  return -8;   // field not closed
+  return -8; // field not closed
 }
 
 // -------------------------------------------------------
-QString Subcircuit::netlist()
-{
-  QString s = Model+":"+Name;
+QString Subcircuit::netlist() {
+  QString s = Model + ":" + Name;
 
   // output all node names
   for (Port *p1 : Ports)
-    s += " "+p1->Connection->Name;   // node names
+    s += " " + p1->Connection->Name; // node names
 
   // type for subcircuit
-  QString f = misc::properFileName(Props.first()->Value);
-  s += " Type=\""+misc::properName(f)+"\"";
+  QString f = misc::properFileName(Props.at(0)->Value);
+  s += " Type=\"" + misc::properName(f) + "\"";
 
   // output all user defined properties
-  for(Property *pp = Props.next(); pp != 0; pp = Props.next())
-    s += " "+pp->Name+"=\""+pp->Value+"\"";
+  for (qsizetype i = 1; i < Props.size(); i++)
+    s += " " + Props.at(i)->Name + "=\"" + Props.at(i)->Value + "\"";
   return s + '\n';
 }
 
-QString Subcircuit::spice_netlist(bool)
-{
-    QString s;
-    QString f = misc::properFileName(Props.first()->Value);
-    s += spicecompat::check_refdes(Name,SpiceModel);
-    for (Port *p1 : Ports) {
-        QString nam = p1->Connection->Name;
-        if (nam=="gnd") nam = "0";
-        s += " "+nam;   // node names
-    }
-    s += " " + misc::properName(f);
-    for(Property *pp = Props.next(); pp != 0; pp = Props.next()) {
-        s += QString(" %1=%2").arg(pp->Name).arg(spicecompat::normalize_value(pp->Value));
-    }
-    s += "\n";
-    return s;
+QString Subcircuit::spice_netlist(bool) {
+  QString s;
+  QString f = misc::properFileName(Props.at(0)->Value);
+  s += spicecompat::check_refdes(Name, SpiceModel);
+  for (Port *p1 : Ports) {
+    QString nam = p1->Connection->Name;
+    if (nam == "gnd")
+      nam = "0";
+    s += " " + nam; // node names
+  }
+  s += " " + misc::properName(f);
+  for (qsizetype i = 1; i < Props.size(); i++) {
+    s += QString(" %1=%2").arg(
+        Props.at(i)->Name, spicecompat::normalize_value(Props.at(i)->Value));
+  }
+  s += "\n";
+  return s;
 }
 
 // -------------------------------------------------------
-QString Subcircuit::vhdlCode(int)
-{
-  QString f = misc::properFileName(Props.first()->Value);
+QString Subcircuit::vhdlCode(int) {
+  QString f = misc::properFileName(Props.at(0)->Value);
   QString s = "  " + Name + ": entity Sub_" + misc::properName(f);
 
   // output all user defined properties
-  Property *pr = Props.next();
-  if (pr) {
+  if (Props.at(1) != nullptr) {
     s += " generic map (";
-    s += pr->Value;
-    for(pr = Props.next(); pr != 0; pr = Props.next())
-      s += ", " + pr->Value;
+    s += Props.at(1)->Value;
+    for (qsizetype i = 2; i < Props.size(); i++) {
+      s += ", " + Props.at(i)->Value;
+    }
     s += ")";
   }
 
@@ -257,11 +257,11 @@ QString Subcircuit::vhdlCode(int)
   s += " port map (";
   QListIterator<Port *> iport(Ports);
   Port *pp = iport.next();
-  if(pp)
+  if (pp)
     s += pp->Connection->Name;
   while (iport.hasNext()) {
     pp = iport.next();
-    s += ", "+pp->Connection->Name;   // node names
+    s += ", " + pp->Connection->Name; // node names
   }
 
   s += ");\n";
@@ -269,30 +269,28 @@ QString Subcircuit::vhdlCode(int)
 }
 
 // -------------------------------------------------------
-QString Subcircuit::verilogCode(int)
-{
-  QString f = misc::properFileName(Props.first()->Value);
+QString Subcircuit::verilogCode(int) {
+  QString f = misc::properFileName(Props.at(0)->Value);
   QString s = "  Sub_" + misc::properName(f);
 
   // output all user defined properties
-  Property *pr = Props.next();
-  if (pr) {
+  if (Props.at(1) != nullptr) {
     s += " #(";
-    s += misc::Verilog_Param(pr->Value);
-    for(pr = Props.next(); pr != 0; pr = Props.next())
-      s += ", " + misc::Verilog_Param(pr->Value);
+    s += misc::Verilog_Param(Props.at(1)->Value);
+    for (qsizetype i = 2; i < Props.size(); i++)
+      s += ", " + misc::Verilog_Param(Props.at(i)->Value);
     s += ")";
   }
 
   // output all node names
-  s +=  " " + Name + " (";
+  s += " " + Name + " (";
   QListIterator<Port *> iport(Ports);
   Port *pp = iport.next();
-  if(pp)
+  if (pp)
     s += pp->Connection->Name;
   while (iport.hasNext()) {
     pp = iport.next();
-    s += ", "+pp->Connection->Name;   // node names
+    s += ", " + pp->Connection->Name; // node names
   }
 
   s += ");\n";
@@ -300,7 +298,6 @@ QString Subcircuit::verilogCode(int)
 }
 
 // -------------------------------------------------------
-QString Subcircuit::getSubcircuitFile()
-{
-  return misc::properAbsFileName(Props.getFirst()->Value, containingSchematic);
+QString Subcircuit::getSubcircuitFile() {
+  return misc::properAbsFileName(Props.at(0)->Value, containingSchematic);
 }
diff --git a/qucs/components/switch.cpp b/qucs/components/switch.cpp
index b074067b..7d242f5d 100644
--- a/qucs/components/switch.cpp
+++ b/qucs/components/switch.cpp
@@ -51,7 +51,7 @@ Switch::Switch()
 Component* Switch::newOne()
 {
   Switch *p = new Switch();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0);
   return p;
 }
@@ -76,12 +76,10 @@ QString Switch::netlist()
   s += " "+Ports.at(1)->Connection->Name;
 
   // output all properties
-  Property *p2 = Props.first();
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
-  p2 = Props.next();
-  s += " "+p2->Name+"=\"["+p2->Value+"]\"";
-  for(p2 = Props.next(); p2 != 0; p2 = Props.next())
-    s += " "+p2->Name+"=\""+p2->Value+"\"";
+  s += " "+Props.at(0)->Name+"=\""+Props.at(0)->Value+"\"";
+  s += " "+Props.at(1)->Name+"=\"["+Props.at(1)->Value+"]\"";
+  for(int i=2;i<Props.size();i++)
+    s += " "+Props.at(i)->Name+"=\""+Props.at(i)->Value+"\"";
 
   return s + '\n';
 }
@@ -163,7 +161,7 @@ QString Switch::spice_netlist(bool)
 // -------------------------------------------------------
 void Switch::createSymbol()
 {
-  if(Props.getFirst()->Value != "on") {
+  if(Props.front()->Value != "on") {
     Lines.append(new qucs::Line(-15,  0, 15,-15,QPen(Qt::darkBlue,2)));
     y1 = -17;
   }
diff --git a/qucs/components/tff_SR.cpp b/qucs/components/tff_SR.cpp
index da4ffd06..00d604f9 100644
--- a/qucs/components/tff_SR.cpp
+++ b/qucs/components/tff_SR.cpp
@@ -44,7 +44,7 @@ tff_SR::tff_SR()
 Component * tff_SR::newOne()
 {
   tff_SR * p = new tff_SR();
-  p->Props.getFirst()->Value = Props.getFirst()->Value; 
+  p->Props.front()->Value = Props.front()->Value; 
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/tr_sim.cpp b/qucs/components/tr_sim.cpp
index 1a624574..82f31d95 100644
--- a/qucs/components/tr_sim.cpp
+++ b/qucs/components/tr_sim.cpp
@@ -119,20 +119,17 @@ QString TR_Sim::spice_netlist(bool isXyce)
 
 void TR_Sim::recreate(Schematic*)
 {
-  Property *pp = Props.first();
-  if((pp->Value == "list") || (pp->Value == "const")) {
+  if((Props.at(0)->Value == "list") || (Props.at(0)->Value == "const")) {
     // Call them "Symbol" to omit them in the netlist.
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    Props.next()->Name = "Values";
+    Props.at(1)->Name = "Symbol";
+    Props.at(1)->display = false;
+    Props.at(2)->Name = "Symbol";
+    Props.at(2)->display = false;
+    Props.at(3)->Name = "Values";
   }
   else {
-    Props.next()->Name = "Start";
-    Props.next()->Name = "Stop";
-    Props.next()->Name = "Points";
+    Props.at(1)->Name = "Start";
+    Props.at(2)->Name = "Stop";
+    Props.at(3)->Name = "Points";
   }
 }
diff --git a/qucs/components/vacomponent.cpp b/qucs/components/vacomponent.cpp
index 85d80f7f..09879974 100644
--- a/qucs/components/vacomponent.cpp
+++ b/qucs/components/vacomponent.cpp
@@ -107,7 +107,7 @@ Component *vacomponent::newOne(QString filename)
 {
   vacomponent * p = new vacomponent(filename);
   if (Props.count())
-      p->Props.getFirst()->Value = Props.getFirst()->Value;
+      p->Props.front()->Value = Props.front()->Value;
   p->recreate(0);
   return p;
 
diff --git a/qucs/components/verilogfile.cpp b/qucs/components/verilogfile.cpp
index ab473500..00c6bd7e 100644
--- a/qucs/components/verilogfile.cpp
+++ b/qucs/components/verilogfile.cpp
@@ -44,7 +44,7 @@ Verilog_File::Verilog_File()
 Component* Verilog_File::newOne()
 {
   Verilog_File *p = new Verilog_File();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0);
   return p;
 }
@@ -90,7 +90,7 @@ QString Verilog_File::verilogCode(int)
 // entity in this file.
 QString Verilog_File::loadFile()
 {
-  QString s, File(Props.getFirst()->Value);
+  QString s, File(Props.front()->Value);
   QFileInfo Info(File);
   if(Info.isRelative())
     File = QucsSettings.QucsWorkDir.filePath(File);
@@ -162,7 +162,7 @@ void Verilog_File::createSymbol()
 QString Verilog_File::getSubcircuitFile()
 {
   // construct full filename
-  QString FileName = Props.getFirst()->Value;
+  QString FileName = Props.front()->Value;
   return misc::properAbsFileName(FileName);
 }
 
@@ -172,7 +172,7 @@ bool Verilog_File::createSubNetlist(QTextStream *stream)
   ErrText = "";
 
   // check filename
-  QString FileName = Props.getFirst()->Value;
+  QString FileName = Props.front()->Value;
   if(FileName.isEmpty()) {
     ErrText += QObject::tr("ERROR: No file name in %1 component \"%2\".").
       arg(Model).arg(Name);
diff --git a/qucs/components/vfile.cpp b/qucs/components/vfile.cpp
index 7dc2adcd..44ea934d 100644
--- a/qucs/components/vfile.cpp
+++ b/qucs/components/vfile.cpp
@@ -89,7 +89,7 @@ Element* vFile::info(QString& Name, char* &BitmapFile, bool getNewOne)
 QString vFile::getSubcircuitFile()
 {
   // construct full filename
-  QString FileName = Props.getFirst()->Value;
+  QString FileName = Props.front()->Value;
   return misc::properAbsFileName(FileName);
 }
 
@@ -103,12 +103,11 @@ QString vFile::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output file properties
-  Property *p2 = Props.first();
-  s += " "+p2->Name+"=\"{"+getSubcircuitFile()+"}\"";
+  s += " "+Props.at(0)->Name+"=\"{"+getSubcircuitFile()+"}\"";
 
   // output all remaining properties
-  for(p2 = Props.next(); p2 != 0; p2 = Props.next())
-    s += " "+p2->Name+"=\""+p2->Value+"\"";
+  for(int i = 1;i<Props.size();i++)
+    s += " "+Props.at(i)->Name+"=\""+Props.at(i)->Value+"\"";
 
   return s + "\n";
 }
diff --git a/qucs/components/vhdlfile.cpp b/qucs/components/vhdlfile.cpp
index f7628203..07ce89f3 100644
--- a/qucs/components/vhdlfile.cpp
+++ b/qucs/components/vhdlfile.cpp
@@ -43,7 +43,7 @@ VHDL_File::VHDL_File()
 Component* VHDL_File::newOne()
 {
   VHDL_File *p = new VHDL_File();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0);
   return p;
 }
@@ -72,12 +72,11 @@ QString VHDL_File::vhdlCode(int)
     s = "  " + Name + ": entity " + EntityName;
 
     // output all generic properties
-    Property *pr = Props.at(1);
-    if (pr) {
+    if (Props.at(1) != nullptr) {
       s += " generic map (";
-      s += pr->Value;
-      for(pr = Props.next(); pr != 0; pr = Props.next())
-	s += ", " + pr->Value;
+      s += Props.at(1)->Value;
+      for(int i = 2; i < Props.size();i++)
+        s += ", " + Props.at(i)->Value;
       s += ")";
     }
 
@@ -98,7 +97,7 @@ QString VHDL_File::vhdlCode(int)
 // entity in this file.
 QString VHDL_File::loadFile()
 {
-  QString File(Props.getFirst()->Value);
+  QString File(Props.front()->Value);
   QFileInfo Info(File);
   if(Info.isRelative())
     File = QucsSettings.QucsWorkDir.filePath(File);
@@ -177,21 +176,23 @@ void VHDL_File::createSymbol()
   No = 0;
   if(!GenNames.isEmpty())
     No = (GenNames.count(',')) + 1;
-  Property * pr = Props.at(1);
+  auto pr = Props.begin();
+  ++pr;
   for(i=0; i<No; i++) {
-    if (!pr) {
-      pr = new Property(GenNames.section(',', i, i),
+    if (pr == Props.end()) {
+      auto newProp = new Property(GenNames.section(',', i, i),
 			GenDefs.section(',', i, i), true,
 			QObject::tr("generic variable")+
 			" "+QString::number(i+1));
-      Props.append(pr);
-      pr = 0;
+      Props.append(newProp);
+      pr = Props.end()-1;
     }
     else {
-      pr->Description =
+
+      (*pr)->Description =
 	QObject::tr("generic variable")+" "+QString::number(i+1);
-      pr->Name = GenNames.section(',', i, i);
-      pr = Props.next();
+      (*pr)->Name = GenNames.section(',', i, i);
+      pr++;
     }
   }
   // remove remaining properties if necessary
@@ -205,7 +206,7 @@ void VHDL_File::createSymbol()
 QString VHDL_File::getSubcircuitFile()
 {
   // construct full filename
-  QString FileName = Props.getFirst()->Value;
+  QString FileName = Props.front()->Value;
   return misc::properAbsFileName(FileName);
 }
 
@@ -215,7 +216,7 @@ bool VHDL_File::createSubNetlist(QTextStream *stream)
   ErrText = "";
 
   // check filename
-  QString FileName = Props.getFirst()->Value;
+  QString FileName = Props.front()->Value;
   if(FileName.isEmpty()) {
     ErrText += QObject::tr("ERROR: No file name in %1 component \"%2\".").
       arg(Model).arg(Name);
diff --git a/qucs/dialogs/changedialog.cpp b/qucs/dialogs/changedialog.cpp
index d00c9244..d9c006ec 100644
--- a/qucs/dialogs/changedialog.cpp
+++ b/qucs/dialogs/changedialog.cpp
@@ -180,7 +180,7 @@ void ChangeDialog::slotButtReplace()
     if(matches(pc->Model)) {
       QRegularExpressionMatch match = Expr.match(pc->Name);
       if(match.hasMatch())
-        for(Property *pp = pc->Props.first(); pp!=0; pp = pc->Props.next())
+        for(const auto& pp : pc->Props)
           if(pp->Name == PropNameEdit->currentText()) {
             pb = new QCheckBox(pc->Name);
             Dia_Box->addWidget(pb);   
@@ -232,7 +232,7 @@ void ChangeDialog::slotButtReplace()
     for(pc = Doc->Components->first(); pc!=0; pc = Doc->Components->next()) {
       if(pb->text() != pc->Name)  continue;
 
-      for(Property *pp = pc->Props.first(); pp!=0; pp = pc->Props.next()) {
+      for(auto pp : pc->Props) {
         if(pp->Name != PropNameEdit->currentText())  continue;
 
         int tx_Dist, ty_Dist, tmp;
diff --git a/qucs/dialogs/fillfromspicedialog.cpp b/qucs/dialogs/fillfromspicedialog.cpp
index dacfdf48..93d2de81 100644
--- a/qucs/dialogs/fillfromspicedialog.cpp
+++ b/qucs/dialogs/fillfromspicedialog.cpp
@@ -171,7 +171,7 @@ QString fillFromSpiceDialog::convertNumNotation(const QString &value)
 
 void fillFromSpiceDialog::fillCompProps()
 {
-  for(Property *p = Comp->Props.first(); p != 0; p = Comp->Props.next()) {
+  for(Property *p : Comp->Props) {
     QString name = p->Name;
     name = name.toLower();
     if (parsedProps.contains(name)) {
diff --git a/qucs/dialogs/matchdialog.cpp b/qucs/dialogs/matchdialog.cpp
index ff9f15e2..c4d4b51b 100644
--- a/qucs/dialogs/matchdialog.cpp
+++ b/qucs/dialogs/matchdialog.cpp
@@ -1398,7 +1398,7 @@ QString MatchDialog::calcBinomialLines(double r_real, double r_imag, double Z0,
 // Sons. 4th Edition. Pg 256-261
 QString MatchDialog::calcChebyLines(double r_real, double r_imag, double Z0,
                                     double gamma, int order, double Freq) {
-  int N = order - 1; // Number of sections
+  const int N = order - 1; // Number of sections
   if (N > 7)         // So far, it is only available Chebyshev weighting up to 7
              // sections. Probably, it makes no sense to use a higher number of
              // sections because of the losses
@@ -1408,20 +1408,21 @@ QString MatchDialog::calcChebyLines(double r_real, double r_imag, double Z0,
         QObject::tr("Chebyshev weighting for N>7 is not available"));
     return QString("");
   }
+
   QString laddercode;
   double RL = r_real, XL = r_imag;
-  r2z(RL, XL,
-      Z0); // Calculation of the load impedance given the reflection coeffient
-  double sec_theta_m; // =
-                      // cosh((1/(1.*N))*acosh((1/gamma)*fabs((RL-Z0)/(Z0+RL)))
-                      // );
-  // double sec_theta_m = cosh((1/(1.*N))*acosh(fabs(log(RL/Z0)/(2*gamma))) );
-  (fabs(log(RL / Z0) / (2 * gamma)) < 1)
-      ? sec_theta_m = 0
-      : sec_theta_m =
-            cosh((1 / (1. * N)) * acosh(fabs(log(RL / Z0) / (2 * gamma))));
-
-  double w[N];
+  r2z(RL, XL, Z0); // Calculation of the load impedance given the reflection coefficient
+
+  double sec_theta_m = 0.0;
+  double log_ratio = log(RL / Z0) / (2 * gamma);
+
+  if (fabs(log_ratio) < 1) {
+      sec_theta_m = 0.0;
+  } else {
+      sec_theta_m = cosh((1.0 / N) * acosh(fabs(log_ratio)));
+  }
+
+  std::vector<double> w(N,0.0);
 
   switch (N) // The weights are calculated by equating the reflection coeffient
              // formula to the N-th Chebyshev polinomial
diff --git a/qucs/dialogs/sweepdialog.cpp b/qucs/dialogs/sweepdialog.cpp
index b0567e20..ef582555 100644
--- a/qucs/dialogs/sweepdialog.cpp
+++ b/qucs/dialogs/sweepdialog.cpp
@@ -173,7 +173,6 @@ Graph* SweepDialog::setBiasPoints(QHash<QString,double> *NodeVals)
   QString DataSet = Info.absolutePath() + QDir::separator() + Doc->DataSet;
 
   Node *pn;
-  Element *pe;
 
   // Note 1:
   // Invalidate it so that "Graph::loadDatFile()" does not check for the previously loaded time.
diff --git a/qucs/extsimkernels/spicelibcompdialog.cpp b/qucs/extsimkernels/spicelibcompdialog.cpp
index d24c080d..18f46e94 100644
--- a/qucs/extsimkernels/spicelibcompdialog.cpp
+++ b/qucs/extsimkernels/spicelibcompdialog.cpp
@@ -474,25 +474,25 @@ bool SpiceLibCompDialog::setCompProps()
     sympath = QDir(sch_dir).relativeFilePath(sympath);
   }
 
-  Property *pp = comp->Props.first();
-  pp->Value = libpath;
-  pp->display = chbShowLib->isChecked();
-  pp = comp->Props.next();
-  pp->Value = cbxSelectSubcir->currentText();
-  pp->display = chbShowModel->isChecked();
-  pp = comp->Props.next();
+  auto pp = comp->Props.begin();
+  (*pp)->Value = libpath;
+  (*pp)->display = chbShowLib->isChecked();
+  pp++;
+  (*pp)->Value = cbxSelectSubcir->currentText();
+  (*pp)->display = chbShowModel->isChecked();
+  pp++;
   if (rbAutoSymbol->isChecked()) {
-    pp->Value = "auto";
+    (*pp)->Value = "auto";
   } else if (rbSymFromTemplate->isChecked()) {
-    pp->Value = listSymPattern->currentItem()->text();
+    (*pp)->Value = listSymPattern->currentItem()->text();
   } else if (rbUserSym->isChecked()) {
-    pp->Value = sympath;
+    (*pp)->Value = sympath;
   }
-  pp = comp->Props.next();
-  pp->Value = edtParams->text();
-  pp->display = chbShowParams->isChecked();
-  pp = comp->Props.next();
-  pp->Value = QString(pin_string);
+  pp++;
+  (*pp)->Value = edtParams->text();
+  (*pp)->display = chbShowParams->isChecked();
+  pp++;
+  (*pp)->Value = QString(pin_string);
   Doc->recreateComponent(comp);
   Doc->viewport()->repaint();
   Doc->setChanged(true,true);
diff --git a/qucs/mouseactions.cpp b/qucs/mouseactions.cpp
index 8647610a..fdd59788 100644
--- a/qucs/mouseactions.cpp
+++ b/qucs/mouseactions.cpp
@@ -61,7 +61,9 @@ QAction *formerAction; // remember action before drag n'drop etc.
 MouseActions::MouseActions(QucsApp *App_)
 {
     App = App_;          // pointer to main app
-    selElem = nullptr;         // no component/diagram is selected
+    if(selElem != nullptr){
+      selElem = nullptr;         // no component/diagram is selected
+    }
     isMoveEqual = false; // mouse cursor move x and y the same way
     focusElement = 0;    //element being interacted with mouse
 
@@ -69,7 +71,8 @@ MouseActions::MouseActions(QucsApp *App_)
     // initialize menu appearing by right mouse button click on component
     ComponentMenu = new QMenu(QucsMain);
     focusMEvent = new QMouseEvent(QEvent::MouseButtonPress,
-                                  QPoint(0, 0),
+                                  QPointF(0, 0),
+                                  QPointF(0, 0),
                                   Qt::NoButton,
                                   Qt::NoButton,
                                   Qt::NoModifier);
diff --git a/qucs/qt3_compat/q3ptrlist.h b/qucs/qt3_compat/q3ptrlist.h
index 5ea114f1..cebdf52a 100644
--- a/qucs/qt3_compat/q3ptrlist.h
+++ b/qucs/qt3_compat/q3ptrlist.h
@@ -109,8 +109,8 @@ class Q3PtrList
     int	  at() const			{ return Q3GList::at(); }
     type *current()  const		{ return (type *)Q3GList::get(); }
     Q3LNode *currentNode()  const	{ return Q3GList::currentNode(); }
-    type *getFirst() const		{ return (type *)Q3GList::cfirst(); }
-    type *getLast()  const		{ return (type *)Q3GList::clast(); }
+    type *front() const		        { return (type *)Q3GList::cfirst(); }
+    type *back()  const		        { return (type *)Q3GList::clast(); }
     type *first()			{ return (type *)Q3GList::first(); }
     type *last()			{ return (type *)Q3GList::last(); }
     type *next()			{ return (type *)Q3GList::next(); }
diff --git a/qucs/qucs.cpp b/qucs/qucs.cpp
index b01b1f01..8d5e3882 100644
--- a/qucs/qucs.cpp
+++ b/qucs/qucs.cpp
@@ -2182,7 +2182,7 @@ void QucsApp::updatePortNumber(QucsDoc *currDoc, int No)
     Schematic *Doc = (Schematic*)w;
     for(Component *pc=Doc->Components->last(); pc!=0; ) {
       if(pc->Model == Model) {
-        File = pc->Props.getFirst()->Value;
+        File = pc->Props.front()->Value;
         if((File == pathName) || (File == Name)) {
           pc_tmp = Doc->Components->prev();
           Doc->recreateComponent(pc);  // delete and re-append component
diff --git a/qucs/schematic.cpp b/qucs/schematic.cpp
index b927d2dd..1edbdc62 100644
--- a/qucs/schematic.cpp
+++ b/qucs/schematic.cpp
@@ -1914,7 +1914,7 @@ int Schematic::adjustPortNumbers()
             if (pc->Model == "Port") {
                 countPort++;
 
-                Str = pc->Props.getFirst()->Value;
+                Str = pc->Props.front()->Value;
                 // search for matching port symbol
                 for (pp = SymbolPaints.first(); pp != 0; pp = SymbolPaints.next()) {
                     if (pp->Name == ".PortSym ") {
@@ -2530,8 +2530,9 @@ void Schematic::contentsDropEvent(QDropEvent *Event)
     auto ev_pos = Event->pos();
     QPoint inModel = contentsToModel(ev_pos);
 #endif
-    QMouseEvent e(QEvent::MouseButtonPress, ev_pos, Qt::LeftButton, Qt::NoButton, Qt::NoModifier);
+    //QMouseEvent e(QEvent::MouseButtonPress, ev_pos, Qt::LeftButton, Qt::NoButton, Qt::NoModifier);
 
+    QMouseEvent e(QEvent::MouseButtonPress, ev_pos, mapToGlobal(ev_pos), Qt::LeftButton, Qt::NoButton, Qt::NoModifier);
 
     App->view->MPressElement(this, &e, inModel.x(), inModel.y());
 
@@ -2633,11 +2634,14 @@ void Schematic::contentsDragMoveEvent(QDragMoveEvent *Event)
         }
 
 #if QT_VERSION >= 0x060000
-        QMouseEvent e(QEvent::MouseMove,
+        auto ev_pos = Event->position();
+        /*QMouseEvent e(QEvent::MouseMove,
                       Event->position(),
                       Qt::NoButton,
                       Qt::NoButton,
-                      Qt::NoModifier);
+                      Qt::NoModifier);*/
+        QMouseEvent e(QEvent::MouseButtonPress, ev_pos, mapToGlobal(ev_pos), Qt::LeftButton, Qt::NoButton, Qt::NoModifier);
+
 #else
         QMouseEvent e(QEvent::MouseMove, Event->pos(), Qt::NoButton, Qt::NoButton, Qt::NoModifier);
 #endif
diff --git a/qucs/schematic_element.cpp b/qucs/schematic_element.cpp
index 3226c072..4527dda3 100644
--- a/qucs/schematic_element.cpp
+++ b/qucs/schematic_element.cpp
@@ -2504,33 +2504,40 @@ bool Schematic::distributeVertical()
 // digital sources and sets them accordingly.
 void Schematic::setComponentNumber(Component *c)
 {
-    Property *pp = c->Props.getFirst();
-    if(!pp) return;
-    if(pp->Name != "Num") return;
-
-    int n=1;
-    QString s = pp->Value;
-    QString cSign = c->Model;
-    Component *pc;
-    // First look, if the port number already exists.
-    for(pc = Components->first(); pc != 0; pc = Components->next())
-        if(pc->Model == cSign)
-            if(pc->Props.getFirst()->Value == s) break;
-    if(!pc) return;   // was port number not yet in use ?
-
-    // Find the first free number.
-    do
-    {
-        s  = QString::number(n);
-        // look for existing ports and their numbers
-        for(pc = Components->first(); pc != 0; pc = Components->next())
-            if(pc->Model == cSign)
-                if(pc->Props.getFirst()->Value == s) break;
+    if(!c->Props.isEmpty()){
+        auto pp = c->Props.front();
+        if(pp != nullptr){
+            if(pp->Name != "Num") return;
+
+            int n = 1;
+            QString s = pp->Value;
+            QString cSign = c->Model;
+            Component *pc =Components->first();
+            // First look, if the port number already exists.
+            for(; pc != 0; pc = Components->next()){
+                if(pc->Model == cSign){
+                    if(pc->Props.front()->Value == s) {break;}
+                }
+            }
+            if(!pc) return;   // was port number not yet in use ?
 
-        n++;
+            // Find the first free number.
+            do
+            {
+                s  = QString::number(n);
+                // look for existing ports and their numbers
+                pc = Components->first();
+                for(; pc != 0; pc = Components->next()){
+                    if(pc->Model == cSign){
+                        if(pc->Props.front()->Value == s) {break;}
+                    }
+                }
+                n++;
+            }
+            while(pc);     // found not used component number
+            pp->Value = s; // set new number
+        }
     }
-    while(pc);     // found not used component number
-    pp->Value = s; // set new number
 }
 
 // ---------------------------------------------------
diff --git a/qucs/schematic_file.cpp b/qucs/schematic_file.cpp
index 798fb316..8855dcde 100644
--- a/qucs/schematic_file.cpp
+++ b/qucs/schematic_file.cpp
@@ -1629,7 +1629,7 @@ bool Schematic::throughAllComps(QTextStream *stream, int& countInit,
 	continue;
       if(!isVerilog && pc->Model == "Verilog")
 	continue;
-      s = pc->Props.getFirst()->Value;
+      s = pc->Props.front()->Value;
       if(s.isEmpty()) {
         ErrText->appendPlainText(QObject::tr("ERROR: No file name in %1 component \"%2\".").
 			arg(pc->Model).
@@ -2105,9 +2105,9 @@ int Schematic::prepareNetlist(QTextStream& stream, QStringList& Collect,
              QObject::tr("ERROR: Only one digital simulation allowed."));
           return -10;
         }
-        if(pc->Props.getFirst()->Value != "TimeList")
+        if(pc->Props.front()->Value != "TimeList")
           isTruthTable = true;
-	      if(pc->Props.getLast()->Value != "VHDL")
+	      if(pc->Props.back()->Value != "VHDL")
 	        isVerilog = true;
         allTypes |= isDigitalComponent;
 	      isAnalog = false;
diff --git a/qucs/spicecomponents/sp_nutmeg.cpp b/qucs/spicecomponents/sp_nutmeg.cpp
index 3363c3a9..3d2f92b0 100644
--- a/qucs/spicecomponents/sp_nutmeg.cpp
+++ b/qucs/spicecomponents/sp_nutmeg.cpp
@@ -85,11 +85,11 @@ QString NutmegEquation::getEquations(QString sim, QStringList &dep_vars)
     else
         match = sim.startsWith(used_sim);
     if ( match || used_sim == "all" ) {
-        Property *pp = Props.first();
-        pp = Props.next();
-        for (;pp!=0;pp=Props.next()) {
-            s += QString("let %1 = %2\n").arg(pp->Name).arg(pp->Value);
-            dep_vars.append(pp->Name);
+        auto pp = Props.begin();
+        pp++;
+        for ( ; pp != Props.end() ; ++pp) {
+            s += QString("let %1 = %2\n").arg((*pp)->Name).arg((*pp)->Value);
+          dep_vars.append((*pp)->Name);
         }
     }
     return s;
diff --git a/qucs/spicecomponents/spicelibcomp.cpp b/qucs/spicecomponents/spicelibcomp.cpp
index 8e0f4600..c0acf0ee 100644
--- a/qucs/spicecomponents/spicelibcomp.cpp
+++ b/qucs/spicecomponents/spicelibcomp.cpp
@@ -59,7 +59,7 @@ SpiceLibComp::SpiceLibComp()
 Component* SpiceLibComp::newOne()
 {
   SpiceLibComp *p = new SpiceLibComp();
-  p->Props.getFirst()->Value = Props.getFirst()->Value;
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0);
   return p;
 }