Qt 6 Transition Guide - new replacement

[Nixellion]

Found another thing that changed:

QPalette.Background was long obsolete, but now using it causes an error, has to be replaced with QPalette.ColorRole.Window. And all calls to QPallete.X should go to QPalette.ColorRole.

At least in my code specifically I had this:

palette = QtGui.QPalette(self.palette())
palette.setColor(palette.Background QtCore.Qt.transparent)

And it was breaking the code and showing an error.

Replacing it with:

palette = QtGui.QPalette(self.palette())
palette.setColor(palette.ColorRole.Window, QtCore.Qt.transparent)

Fixed the problem.

[mottosso]

Thanks for this, any chance you can put this in the README towards the bottom with the other transition notes?

[MHendricks]

Documenting this is covered in the changes to CAVEATS.md in #431.