 			name: "fill"
 
 		@knobOverlay = new Layer
-			backgroundColor: null
 			name: "knobOverlay"
 
 		@sliderOverlay = new Layer
-			backgroundColor: null
 			name: "sliderOverlay"
 
 		super options

		@knob.draggable.momentumOptions = {friction: 5, tolerance: 0.25}
		@knob.draggable.bounce = false
		@knob.draggable.propagateEvents = false
		@knob.borderRadius = @knobOverlay.borderRadius = @knobSize / 2

		# If hitArea isn't defined, remove the overlays
		if not @hitArea

		@fill.style.borderRadius = "#{radius}px 0 0 #{radius}px"

	_setOverlayRadius: =>
		@knobOverlay.borderRadius = (@knob.borderRadius * 2) + (@hitArea / 4)

	@define "bounded", @simpleProperty("bounded", false)

