Comment 14 for bug 1871644

This just became even more prominent in 95 with colorways. We need a way to support this with alpha visuals as XShape is neither available on Wayland nor on X11 with HW Webrender - i.e. it's only available in legacy fallback paths. As the default theme supports this (even though with a grey corner), I suppose this is not really a graphics but rather a theme issue.

Emilio, do you happen to know how the default theme gets its corners and what would need to be done to make it work for other themes as well?