我怎么都觉得代码应该放入preWindowShellClose中，而不是postWindowClose中，好像代码执行到postWindowClose后是没有后悔的余地了，窗口基本不可避免的被关掉。
/**
* Performs arbitrary actions after the window is closed.
* <p>
* This method is called after the window's controls have been disposed.
* Clients must not call this method directly (although super calls are
* okay). The default implementation does nothing. Subclasses may override.
* </p>
*/
public void postWindowClose() {
// do nothing
}