Ends a batch of drawing commands. The last end in a list of nested calls does a refresh and draws the objects on the screen. 

	w=gfx.Window(); 
	w:batchBegin()
	function r() return math.random()*300; end 
	for i=1,1000 do
		w:line(r(),r(),r(),r()); 
	end
	w:batchEnd()