AlQ authored 3 years ago and Ammar Nejati committed 2 years ago

* NOTE:
The CMake command to find Qt6 include files and libraries is the following:
```
OPT_DIR="$HOME/.local/opt"
QT_CMAKE_DIR="$OPT_DIR/Qt/6.2.3/gcc_64/lib/cmake"
cmake -S . -B build -DCMAKE_PREFIX_PATH="$OPT_DIR;$QT_CMAKE_DIR"
```

The libraries `libEGL.dll` and `libGLESv2.dll` are not part of the Qt6
distribution. Instead, `Qt6OpenGL.dll`, `Qt6OpenGLWidgets.dll` and
`opengl32sw.dll` must be included in the Windows installer.

See
<https://doc.qt.io/qt-6/windows-deployment.html>
<https://doc.qt.io/qt-6/opengl-changes-qt6.html>

`Qt::AA_UseHighDpiPixmaps` is deprecated: High-DPI pixmaps are always enabled. This attribute no longer has any effect.

Error: use of deleted function ‘constexpr void
operator+(QFlags<SessionFlags::ERoles>::enum_type, int)’

In Qt 6, QMetaType::registerComparators have been removed. The metatype system
will instead know about those automatically.
See <https://www.qt.io/blog/whats-new-in-qmetatype-qvariant>.

The signal `void buttonClicked(int id)` is obsolete in Qt6.

The signal `void currentIndexChanged(const QString &text)` is obsolete in Qt6.
Instead, one should obtain the index and then use `QComboBox::itemText` to get
the text.

`QRegExp` is deprecated in Qt6; instead `QRegularExpression` and
`QRegularExpressionMatch` must be used.

The direct conversion is not allowed in Qt6.

The proper Qt6 constructor is QVector(InputIterator first, InputIterator last)