"Use colors from system theme" causes the background to become transparent
When "Use colors from system theme" is checked, the background color ends up with a zero alpha (transparent). This makes it all the way to the window surface buffer and to the compositor. Since gnome-terminal also tells the compositor that the surface is opaque (wl_surface::set_opaque_region
), this causes repaint artifacts in the compositor. On mutter, the background ends up a glitchy mess of old surface contents. KWin works fine in the steady state, but the background becomes transparent while moving the window.
Quoting the Wayland spec:
The opaque region is an optimization hint for the compositor that lets it optimize the redrawing of content behind opaque regions. Setting an opaque region is not required for correct behaviour, but marking transparent content as opaque will result in repaint artifacts.
(Note: I don't know what "system theme" means on my system. It's possible that whether this bug happens varies depending on where that data comes from, if it includes the alpha channel.)
As far as I can tell, gnome-terminal isn't doing any GPU rendering itself, so this isn't a GPU driver bug (I checked the framebuffer contents in memory and the zero alpha does indeed show up on the gnome-terminal side).
System: Apple M1 running gnome-terminal 3.46.7 (Asahi Linux with mesa-asahi-edge
).