 		@dom.oncontextmenu = => false
 
 		tick = =>
+			return if not _self.isRunning
+
 			tickCount += 1
 			_self.triggerEvent "update", {"tickCount": tickCount}
 			clearCanvas()

		setInterval(tick, 1000 / @fps)
		clearCanvas = =>
			@context.clearRect(0, 0, _self.width, _self.height)


	append: (shape) ->

		@context.textBaseline = 'top'

		tickCount = 0
		@isRunning = true;

		# API
		@shapes = []
