This prevents some of our generic object implementation tests
from working with gesture objects. Instead, add g_return_if_fail
checks in all the gesture constructors.
This signal will always be paired with a ::pressed signal, unless
the sequence is cancelled, or the controller is reset. the n_press
argument in the signal always matches the ::press signal one, even
if GtkGestureMultiPress::stopped was emitted in between.
The current sequence (as per gtk_gesture_single_get_current_sequence)
is used to find out the coordinates. And only emit ::pressed if the
gesture began through a GDK_BUTTON_PRESS/TOUCH_BEGIN (eg. not due to
an extra touch being lifted)
This gesture handles any number of clicks, ensuring multiple presses
stay within thresholds and timeouts. When anything of that happens,
the gesture is reset and press count starts from 1 again.
Optionally, the gesture can be given a rectangle, used in in presses > 1
to ensure the consecutive presses happen on user imposed areas.
