Get a reference to data at self as a SDLMouseButtonUpEvent

Require: is_mouse_button_up

Property definitions

sdl2 $ SDLEventBuffer :: to_mouse_button_up
	# Get a reference to data at `self` as a `SDLMouseButtonUpEvent`
	#
	# Require: `is_mouse_button_up`
	fun to_mouse_button_up: SDLMouseButtonUpEvent `{ return self; `}
lib/sdl2/events.nit:86,2--89,65