code: public void startScroll(int startX, int startY, int dx, int dy) {
          startScroll(startX, startY, dx, dy, DEFAULT_DURATION);
      }
docs: Start scrolling by providing a starting point and the distance to travel.
  The scroll will use the default value of 250 milliseconds for the
  duration.
  
  @param startX Starting horizontal scroll offset in pixels. Positive
  numbers will scroll the content to the left.
  @param startY Starting vertical scroll offset in pixels. Positive numbers
  will scroll the content up.
  @param dx Horizontal distance to travel. Positive numbers will scroll the
  content to the left.
  @param dy Vertical distance to travel. Positive numbers will scroll the
  content up.