 		if let vc = leftView {
 			let w: CGFloat = vc.width
 			let h: CGFloat = vc.height
-			let d: Double = Double(0 == velocity ? SideNavigationViewController.animationDuration : fmax(0.1, fmin(1, Double(vc.x / velocity))))
+			let d: Double = Double(0 == velocity ? animationDuration : fmax(0.1, fmin(1, Double(vc.x / velocity))))
 			
 			MaterialAnimation.animationWithDuration(d, animations: {
 				vc.position = CGPointMake(-w / 2, h / 2)
+				self.backdropLayer.hidden = true
 			}) {
-				SideNavigationViewController.backdropLayer.hidden = true
 				self.isUserInteractionEnabled = true
 				self.toggleStatusBar(false)
 			}

	/**
		:name:	backdropColor
	*/
	public static var backdropColor: UIColor? {
		didSet {
			backdropLayer.backgroundColor = backdropColor?.colorWithAlphaComponent(backdropOpacity).CGColor
		}

	//
	internal func prepareLeftView() {
		// container
		leftView = MaterialView(frame: CGRectMake(0, 0, leftViewControllerWidth, view.frame.height))
		view.addSubview(leftView!)
		
		MaterialAnimation.animationDisabled({
