code: public boolean isSeparatorAt(int x, int y)
      {
          return containsSeparatorAt(x, y, bsep) ||
                 containsSeparatorAt(x, y, hsep) ||
                 containsSeparatorAt(x, y, vsep);
      }
docs: Checks if a point is covered by a separator.
  @param x the point x coordinate
  @param y the point y coordinate
  @return <code>true</code> if any of the separators in this set covers the specified point