Bug: Degraded window depth detection

[joshqou]

Upgrading from 6336223 to 9bfb361, the dock will take several seconds to hide when making a video player fullscreen in xwayland applications. Wayland applications such as Firefox are not effected

[joshqou]

This issue seems to also effect games running in xwayland. Switching windows while the game is fullscreen can sometimes get the dock to hide.

[joshqou]

@icedman The dock absorbs clicks in fullscreen windows too, even when not visible. I've also seen the dock appear in the lock screen.