"Professional CMake" book suggest the following:
"Targets should build successfully with or without compiler support for precompiled headers. It
should be considered an optimization, not a requirement. In particular, do not explicitly include a
precompile header (e.g. stdafx.h) in the source code, let CMake force-include an automatically
generated precompile header on the compiler command line instead. This is more portable across
the major compilers and is likely to be easier to maintain. It will also avoid warnings being
generated from certain code checking tools like iwyu (include what you use)."
Therefore, removed the "#include <PreCompiled.h>" from sources, also
there is no need for the "#ifdef _PreComp_" anymore
Previously the code defined compatiblity usings in `QtOpenGL.h` header,
which I think was added for backwards compatiblity with previous Qt
OpenGL widgets.
As far as I can tell, this is not necessary anymore, and can be cleaned
up.
- it was frequently requested and people now even published videos since I documented this hidden feature in the Wiki.
However, for a user it is a nightmare without a UI and users who like a bright background need to change the button color to keep the buttons visible.
* Explicitly include some missing headers
* Use 'static const char*' for XPM icon
* Skip template parameters for qMakePair
* Constructor of QFileInfo is marked as 'explicit' now
* QString::fromLatin1() also accepts a QByteArray
* QDateTime::fromTime_t() is deprecated in Qt5 and has been removed in Qt6. Use QDateTime::fromSecsSinceEpoch()
* QDateTime::toTime_t() is deprecated in Qt5 and has been removed in Qt6. Use QDateTime::toSecsSinceEpoch()
* QApplication::globalStrut() is deprecated. Don't use it any more.
* QWidget::isTopLevel() is deprecated, use QWidget::isWindow()
* On lines where the variable type is obvious from inspection, avoid repeating the type using auto.
* When possible use a ranged for loop instead of begin() and end() iterators
