code: protected boolean canChildScrollVertically(View v, boolean checkV, int dx, int x, int y) {
  		if (v instanceof ViewGroup) {
  			final ViewGroup group = (ViewGroup) v;
  
  			final int count = group.getChildCount();
  			// Count backwards - let topmost views consume scroll distance first.
  			for (int i = count - 1; i >= 0; i--) {
  				final View child = group.getChildAt(i);
  
  				final int childLeft = child.getLeft() + supportGetTranslationX(child);
  				final int childRight = child.getRight() + supportGetTranslationX(child);
  				final int childTop = child.getTop() + supportGetTranslationY(child);
  				final int childBottom = child.getBottom() + supportGetTranslationY(child);
  
  				if (x >= childLeft && x < childRight && y >= childTop && y < childBottom
  						&& canChildScrollVertically(child, true, dx, x - childLeft, y - childTop)) {
  					return true;
  				}
  			}
  		}
  
  		return checkV && mOnInterceptMoveEventListener.isViewDraggable(v, dx, x, y);
  	}
docs: Tests scrollability within child views of v given a delta of dx.
  
  @param v      View to test for horizontal scrollability
  @param checkV Whether the view should be checked for draggability
  @param dx     Delta scrolled in pixels
  @param x      X coordinate of the active touch point
  @param y      Y coordinate of the active touch point
  @return true if child views of v can be scrolled by delta of dx.