When `PLASMA_USE_QT_SCALING=1` is set, Plasma uses native Qt scaling. This works fine for integer scale factors, and fixes a lot of bugs (see [[https://bugs.kde.org/show_bug.cgi?id=356446|Bug 356446]] but it introduces a new one: with non-integer scale factors, text becomes blurry and pixellated because of a bug in NativeRendering.
QQC2-desktop-style forces the use of Qt font rendering for non-integer scale factors, successfully working around the problem. But PlasmaComponents QML objects don't implement the same workaround, so we see the issue in Plasma. This patch fixes that, and gets us one step closer to being able to use Qt scaling in Plasmashell.
There is no effect when `PLASMA_USE_QT_SCALING=1` is not being used.
FIXED-IN 5.13
BUG: 391691