@Override
 protected void doOKAction() {
   mySelectedClass = calcSelectedClass();
   if (mySelectedClass == null) return;
   if (!myClassFilter.isAccepted(mySelectedClass)) {
     Messages.showErrorDialog(
         myTabbedPane.getComponent(),
         SymbolPresentationUtil.getSymbolPresentableText(mySelectedClass) + " is not acceptable");
     return;
   }
   super.doOKAction();
 }