SUMMARY I have a Intel HD 630 + nvidia 1050 Ti dual GPU laptop. When using PRIME render offload, the panel, application launcher, and the system tray applets all turn opaque. SOFTWARE/OS VERSIONS Linux/KDE Plasma: 5.7.2-arch1-1 KDE Plasma Version: 5.19.0 KDE Frameworks Version: 5.71.0 Qt Version: 5.15.0 nvidia Version: 440.82 mesa Version: 20.1.1 Xorg driver: modesetting ADDITIONAL INFORMATION I tried installing optimus-manager and switching to nvidia only mode. Transparency works fine while using that. Changing System Settings > Application Style > Breeze (pencil) > Transparency > Slider changes the transparency of things like the context menus. This works right even when using PRIME render offload.
Update - Workarounds 1) Disabling compositor on startup and enabling it later 2) Switching to XRender backend and switching back to one of the OpenGL backends
I think your friend here is the Shift+Alt+F12 shortcut to toggle compositing without having to mess with the settings.
(In reply to magiblot from comment #2) > I think your friend here is the Shift+Alt+F12 shortcut to toggle compositing > without having to mess with the settings. Yes, that works too
Update - bug still present with nvidia 450.57 driver SOFTWARE/OS VERSIONS Linux/KDE Plasma: 5.7.7-arch1-1 KDE Plasma Version: 5.19.3 KDE Frameworks Version: 5.72.0 Qt Version: 5.15.0 nvidia Version: 450.57 mesa Version: 20.1.3 Xorg driver: modesetting
Can't replicate after a clean install of Arch, nobody else seems to be affected.