sclass ImageSurface_PositionToolTip > ImageSurfaceMouseHandler {

  *(ImageSurface is) {

    if (containsInstance(is.tools, ImageSurface_PositionToolTip)) ret;

    register(is);

  }

  public void mouseMoved aka mouseDragged(MouseEvent e) {

    pcall {

      Pt p = getPt(e);

      S s = str(p);

      var img = is.getImage();

      if (img != null && p.x >= 0 && p.y >= 0

        && p.x < img.getWidth() && p.y < img.getHeight()) {

        IToolTipMaker toolTipMaker = lookupDynamicInterface_v2 IToolTipMaker(img);

        if (toolTipMaker != null)

          s = toolTipMaker.getToolTip(p);

        else

          s += " - " + intToHex_fullLength(img.getRGB(p.x, p.y));

      }

      setToolTip(is, s);

    }

  }

}