code: public void makeVisible() {
      CSSClass cls = new CSSClass(this, "unused");
      cls.setStatement(SVGConstants.CSS_FILL_PROPERTY, SVGConstants.CSS_GREEN_VALUE);
      cls.setStatement(SVGConstants.CSS_FILL_OPACITY_PROPERTY, "0.2");
      cls.setStatement(SVGConstants.CSS_CURSOR_PROPERTY, SVGConstants.CSS_POINTER_VALUE);
      SVGUtil.setAtt(element, SVGConstants.SVG_STYLE_ATTRIBUTE, cls.inlineCSS());
    }
docs: Make the rectangle visible, for debug purposes.