In common situation, the reference of client window is destroyed after parent window unloads (refresh or reload). We can just make the client window have page reloads again by calling window.open() again. It's very inefficient since it causes page reload in client browser, all componets in client window need to be downloaded again. And of course the current state will be destroyed. We need to do start over all things. I want to get reference of client window back again whenever user returns to the original page.
I realized it's not so easy after googling for several hours. But this forum answer works. And this page is my implementation. It works in all major browsers I have (IE8, FF4, Chrome...). You can click open to open a client window and then click reload or leave button.