[3dprinter-general] Bug#951033: Workaround found

[Yann Vernier]

I just mucked about with Cura and tracked down inaccessible buttons to a
lacking implicitWidth for the background of ActionButton in the QML.
However, when digging for more information, I found 

https://github.com/Ultimaker/Cura/issues/5488#issuecomment-588560291

This suggests setting QT_QUICK_CONTROLS_STYLE=material, and in my
testing that does indeed resolve several of the UI bugs, including the
crash when previewing and the misrendered (size, placement, missing
background) buttons. 

I shall see if I can set this in Cura itself, but the quick workaround
would seem a wrapper script that sets the environment variable. Such
tweaks are in fact the main content of the cura script itself (aka
cura_app.py), so something like:

os.environ["QT_QUICK_CONTROLS_STYLE"] = "material"

before the CuraApplication creation (next to last line) should do.