Isn’t this supposed to be a job for the window manager?
For example, my virtualbox install has some mouse pointer bugs on wayland, and I can’t run waydroid on X. These things are weird to me. Shouldn’t window managers abstract all that for the software we run?
The application needs to speak a protocol to be able to use it. If you use a X wm your apps need to be able to talk X’s protocol to work, if you use a Wayland compositor your apps need to be able to talk Wayland’s protocol (or run on Xwayland, which is basically an X server that runs inside Wayland).
The wm/compositor abstractions only work if your apps know how to use them via the correct protocol
I thought that wms worked as full abstraction layers. It helped to reduce my confusion, thanks.
Typically the abstraction to draw elemnts inside a app window is in the application framework, like GTK, Qt, Electron (chromium), etc.
This is also why apps built with the same framework typically have the same problem on wayland (looking at you, electron).
The abstractions you are thinking of is not in the window manager, which only controls things outside of the main app window, like tiling, border, window top bar, etc.
