Creates a new PadController that will associate events from
A null pad may be provided so the controller manages all pad devices generically, it is discouraged to mix
PadController objects with null and non-
pad argument on the same toplevel window, as execution order is not guaranteed.
Be aware that pad events will only be delivered to Windows, so adding a pad controller to any other type of widget will not have an effect.
ActionGroup to trigger actions from
A gdk_source_tablet_pad device, or null to handle all pads
A newly created PadController