(cherry-pick) Simplify tile dismissal
We want floating tiles to be activatable, but also dismiss the effect by clicking on the whitespace.
The current solution doesn't work as a floating tile that is in turn split will pull focus from the children meaning those tiles can't be deleted.
Rather than special casing and z-manipulation we can simplify everything by moving tile dismissal to the root of the effect and appropariately propagating the event.
(cherry picked from commit 7b46f101)