We can just replace window comparisons with coordinate matching, the
cursor corresponding to edges is now set in a capture-phase motion
handler, as cursors aren't set on GdkWindows anymore.
It's not necessary anymore to receive input events. The pan gesture has
been set on the capture phase as the child widgets may capture during
bubbling.
There should be no circumstances where an implicit grab is requested but
no focus exists, there's however circumstances (like windowing grabs taking
input to a different window) where we might get implicit grabs being undone
when then new window didn't create a focus for the pointer itself.
Only if they fall outside the grab widget, in that case the widget holding
the implicit grab won't be receiving events anymore, so we can just undo
it.
We now rely on toplevels receiving and forwarding all the events
the windowing should be able to handle. Event masks are no longer a
way to determine whether an event is deliverable ot a widget.
Events will always be delivered in the three captured/target/bubbled
phases, widgets can now just attach GtkEventControllers and let those
handle the events.
Those are now needless and wrong, as we get guarantees that handled
events will contain widget-relative coordinates. A side effect is
that these events are very possibly not explicitly sent to the
GdkWindow that implementations expect, any extra checks performed
through gtk_gesture_set_window() will be wrong, so the function has
been dropped entirely.
And refurbish cursor management to be set on the GtkWidget. The
input window is not needed anymore to receive events either.
This is no longer set through the GdkWindow, so use the private
GtkWidget API.
The event shall no longer be "directed" to the event window, but the
widget. Getting a enter/leave event is enough now to know whether the
pointer is inside or outside the widget.
Unlike GTK+ grabs which are global to all/one device, the implicit grab
is per focus, which means each may have implicit grabs on different or
the same widget.
Now that gtk_main_do_event() is able to handle pointing events in toplevel
coordinates, forward all of these as is. Just minimal handling is still done
on the gdk side for GDK grab accounting, and toplevel tracking for each
pointer.
Implement target finding per-pointer/touchpoint through GtkPointerFocus and
_gtk_toplevel_pick(). Focus changes are handled through the emission of
crossing events between the old target and the new one.
Each toplevel will keep its own tracking of the current ongoing foci,
add the plumbing that will allow to create/update/remove those as they
come and go.
These objects (tied to a toplevel) track the focus of a pointer/touchpoint.
The info in these basically consists of current toplevel coordinates and the
current target widget.
This function will be useful in other places, such as determining the
widgets that must receive crossing events after pointer picking points
to another widget.
Aborting the application makes it look like an application bug, when
it is the expected thing to do when the Wayland display server goes
way. eg., when the user logs out. The log level is also demoted to
avoid a storm of warnings in the log from all applications whenever
this happens.
This is also what the X11 backend does (see gdk_x_io_error).
https://bugzilla.gnome.org/show_bug.cgi?id=783047
