if (comp==rootPane)
if (!initStageDone)
    protected  void addImpl(Component comp, Object constraints, int index)  {    // If we're adding the rootPane (initialization stages) use super.add.    // Otherwise pass the add onto the content pane.    if (comp==rootPane)    super.addImpl(comp, constraints, index);    else      {        if (isRootPaneCheckingEnabled())          throw new Error("rootPaneChecking is enabled - adding components "                           + "disallowed.");        getContentPane().add(comp,constraints,index);      }  }