public int clampViewPositionVertical(View child, int top, int dy) {
            return 0;
        }
Restrict the motion of the dragged child view along the vertical axis.
The default implementation does not allow vertical motion; the extending
class must override this method and provide the desired clamping.


@param child Child view being dragged
@param top Attempted motion along the Y axis
@param dy Proposed change in position for top
@return The new clamped position for top
app/src/main/java/home/smart/fly/animations/widget/slidepanel/ViewDragHelper.java