[LyX/master] Fix dark/light mode setting and run-time switch with Qt 6.8

[Jürgen Spitzmüller]

Am Mittwoch, dem 23.10.2024 um 20:07 +0200 schrieb Yu Jin:
> so it looks like it's inconsistent. 

I see. Just a shot in the dark: Do things improve if you uncomment
GuiView.cpp:1800 (guiApp->setPalette(guiApp->style()-
>standardPalette());)?

-- 
Jürgen