How to do a popup window like this?
Take this page as an example: http://download.cnet.com/AD-Stream-Recorder/3000-2168_4-10525870.html

If you try to post a comment, this window pop up and the whole page is locked.

![pop up window][1]

Can anyone tell me how this is done?



  [1]: http://i.stack.imgur.com/fZo04.jpg
How to do a popup window like this?
===

Take this page as an example: http://download.cnet.com/AD-Stream-Recorder/3000-2168_4-10525870.html

If you try to post a comment, this window pop up and the whole page is locked.

![pop up window][1]

Can anyone tell me how this is done?



  [1]: http://i.stack.imgur.com/fZo04.jpg