Re-focus on the container on which the cursor hovers over. A
special case is, if there are menus or other subsurfaces open
in the focused container. It will prefer the focused container
as long as there are subsurfaces.
This commit starts caching the previous node as well as the
previous x/y cursor position. Re-calculating the previous
focused node by looking at the current state of the cursor
position does not work, if the environment changes.
7727d54faf