ui/gtk: enable backend to send multi-touch events
GTK3 provides the infrastructure to receive and process multi-touch
events through the "touch-event" signal and the GdkEventTouch type.
Make use of it to transpose events from the host to the guest.
This allows users of machines with hardware capable of receiving
multi-touch events to run guests that can also receive those events
and interpret them as gestures, when appropriate.
An example of this in action can be seen here:
https://fosstodon.org/@slp/
109545849296546767
Signed-off-by: Sergio Lopez <slp@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <
20230526112925.38794-7-slp@redhat.com>