Bug#986821: freecad: Garbled menu makes freecad unusable

[Werner Mayer]

Hi everybody,

I have tested it on my XFCE system to decrease the DPI value to e.g. 80
and then I can confirm that FreeCAD's menus and toolbars are unusable.
Looking through the code I found this line
> QGuiApplication::setHighDpiScaleFactorRoundingPolicy(Qt::HighDpiScaleFactorRoundingPolicy::PassThrough);
After commenting it out the problem is gone.

The line once has been added with
https://github.com/FreeCAD/FreeCAD/pull/4605 and is supposed to fix a
scaling problem on Windows.

As a proper fix I suggest to enable this line for Windows only:
> #if QT_VERSION >= QT_VERSION_CHECK(5,14,0) && defined(Q_OS_WIN)
> QGuiApplication::setHighDpiScaleFactorRoundingPolicy(Qt::HighDpiScaleFactorRoundingPolicy::PassThrough);
> #endif


Btw, FreeCAD built with Qt6 doesn't seem to suffer from this problem.

I hope this helps.

BR,
Werner