code: public void checkZIndex() {
  
          int zIndex = 100000;
          Element parent = m_element.getParentElement();
          while (parent != null) {
              int parentIndex = CmsDomUtil.getCurrentStyleInt(parent, CmsDomUtil.Style.zIndex);
              if (parentIndex > zIndex) {
                  zIndex = parentIndex;
              }
              parent = parent.getParentElement();
          }
          if (zIndex > 100000) {
              getElement().getStyle().setZIndex(zIndex);
          }
      }
docs: Increases the overlay z-index if necessary.<p>