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.
The mouse binding logic is inspired/copied from the
keyboard binding logic; we store a sorted list of the
currently pressed buttons, and trigger a binding when
the currently pressed (or just recently pressed, in
the case of a release binding) buttons, as well as
modifiers/container region, match those of a given
binding.
As the code to execute a binding is not very keyboard
specific, keyboard_execute_command is renamed to
seat_execute_command and moved to where the other
binding handling functions are. The call to
transaction_commit_dirty has been lifted out.
