Facebook Style Message Popup?

My site has a Send Message button next to the link to a users profile. When the user clicks on it (开发者_开发问答using the onClick handler) I want to open a Facebook-style message window, instead of a new window (window.open() method).

It doesn't have to be exactly the same as Facebook's, but I want a similar kind of thing.

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Check out Jquery-UI. they have a lot of popuppable windows. Probably want to couple that with some Ajax, and bam, dynamic message popups.