wmww
Flicker on anchor change
When the anchor is set such that the surface should be stretched across the output, there is a slight flicker as the surface moves first and then resizes. Tested with Rootston, and more prominent when Rootston is running in GDB. This may partly be due to the set_anchor getting called before the set_size, configure, ack_configure dance can happen, and partly due to wlroots moving the surface on the set_anchor instead of waiting for a commit.
Issue is at least partially caused by https://github.com/swaywm/wlroots/issues/1657 (where you can find a much better explanation of what should be happening as well)
Will close once I get things implemented correctly in Mir, and can test there are no other issues (it might be acking the configure too early as well)