code: private static void attachToDecor(Activity activity, SwipeBack swipeBack) {
  		ViewGroup decorView = (ViewGroup) activity.getWindow().getDecorView();
  		ViewGroup decorChild = (ViewGroup) decorView.getChildAt(0);
  
  		decorView.removeAllViews();
  		decorView.addView(swipeBack, LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
  
  		swipeBack.mContentContainer.addView(decorChild, decorChild.getLayoutParams());
  	}
docs: Attaches the swipe back drawer to the window.