Hopefully this helps.

This check doesn't handle tabbed columns properly (it should find and
take the fixed height tile's height); for now just gate it on is_tabbed.

It was only needed to be const fn.

Before this, focus ring/border width was incorrectly rounded only for
layout config, which does not take into account window rules overrides.
This means that setting width in window rules prevented correct rounding
altogether.

Tests didn't check this because window rules weren't tested. This commit
also adds basic window rules random generation, making the tests catch
this problem too.

This is apparently required: Orca expects us to keep track of modifiers
sent in KeyboardMonitor even during an Orca modifier key combo.