Now that we have a global MetaScreen, we can simply have a global
MetaCursorTracker as well. Keep the get_for_screen() API around for
compatibility, though.
The Alt+F7 and Alt+F8 keybinds for moving and resizing windows allow you
to move and resize the window off the screen, so allow the same for the
menu items as well, since they're marked with the same accelerator.
https://bugzilla.gnome.org/show_bug.cgi?id=728617
This doesn't particularly matter, since we fall through into a default
case that does nothing right below, but this matches the other paths
and it prevents us from falling into a trap if we add other event types
below.
If we start a grab op from a keybind / menu, we'll handle the
ButtonPress and drop the grab then, never giving the window a chance
to handle what it needs to do before the grab is dropped.
This means that if you use Alt+F7 to move a window around, move it
to a side-tiling or maximization area, and then left-click, it will
just hang there in the sky.
The entire point of it was to check whether the window was on the
right screen. Since we don't handle multiple screens anymore, we
don't need to check anything anymore.
Looking at the code paths where is_mouse / is_keyboard are used,
all of them should never be run when dealing with a COMPOSITOR
grab op, since they're filtered out above or the method is just
never run during that time.
It's confusing that COMPOSITOR is in here, and requires us to
be funny with other places in code, so just take it out.
pointer->current needs to always be the surface under the pointer,
even when we have a grab. We do need to make sure we keep the focus
surface the same even when we have a grab, though, so add logic
for that.
In order to correctly fix the issue to make sure we only set the
focused surface to NULL during a grab, but not the current surface,
we need to merge update_current_surface back into repick_for_event
so we have more control over the behavior here.
... not when we do an update.
We only repick when we handle events, not when we update. Perhaps
this is a mistake.
Since update runs before handle_event, this means that when we
drop a grab, update will notice the NULL surface, since we haven't
repicked after the event, and then we'll repick the correct surface.
The end result is that you see a root cursor after a grab ends,
rather than the correct window cursor.
This doesn't fix it, since the current surface becomes NULL when
we start the grab. But it does make the code here more correct when
we fix that bug.
