 			self.sideView.zPosition = 1000
 		})
 		
-		prepareViewControllerWithinContainer(sideViewController!, container: sideView)
+		prepareViewControllerWithinContainer(sideViewController, container: sideView)
 		
 		// gestures
 		prepareGestures()

		:name:	close
	*/
	public func close(velocity: CGFloat = 0) {
		let w: CGFloat = sideView.width
		let h: CGFloat = sideView.height
		let d: Double = Double(0 == velocity ? animationDuration : fmax(0.1, fmin(1, Double(sideView.x / velocity))))
		
		toggleStatusBar(false)
		MaterialAnimation.animationWithDuration(d, animations: {
			self.sideView.position = CGPointMake(-w / 2, h / 2)
			self.backdropLayer.hidden = true
		}) {
			self.userInteractionEnabled = true

	//
	internal func prepareMainView() {
		prepareViewControllerWithinContainer(mainViewController, container: view)
		mainViewController.view.translatesAutoresizingMaskIntoConstraints = false
		MaterialLayout.alignToParent(view, child: mainViewController.view)
	}
	
	//
