folder.addCTabFolder2Listener(new CTabFolder2Adapter() {
	@Override
		public void close (CTabFolderEvent event) {
		    System.out.println(" Open popup window, and do some thing");
                    System.out.println("can not cancel this action ? ");
       }
}

boolean res = MyDialog.showConfirmdialog("Are you sure you want to close it ! You will lose the changed data if this page has been modified.");
if (res) {
	System.out.println("yes was selected and this page was closed");
}else{
	event.doit = false;
	System.out.println("No was selected and this event was cancelled");
	return;
}