Took the whole yesterday and a bit of today, but I've got window closing animations working! These turned out to be tricky because they need storing a snapshot of the surface render tree to draw once the app is gone.

Some apps may start destroying their subsurfaces before the main surface, like alacritty with its sctk CSD, making it very easy to miss parts of the window in the snapshot, and therefore in the closing animation.

Also, windows closing to the left no longer shift the view!

#niri