如何在GMail中实现聊天窗口的弹出功能？

I'm not looking for a full implementation, I'm more interested in how they do it. I know they use GWT, but I'd like a more low level answer. Naively, I would start by thinking when you click the popout link they simply open a new window and copy content into it. There are lots of reasons why that won't work out well, so I'm wondering if anyone knows or has ideas on how they do this or how it could be done.I'm not looking for a full implementation, I'm