Can I have multiple viewports in one tab?

[Duncan Marshall]

I'd essentially like to have a Chrome extension page that loads multiple external webpages under one tab in something like iframes.  I say like an iframe because a true iframe won't work for me since some websites fail to load inside iframes.  A webview tag won't work for me either because I want the loaded pages to have installed extensions running on them.  App windows are nice but they're in separate system windows.  If I could some how embed app windows under one browser tab, and not in separate windows, that would be close to what I want.

Is there anything like what I want?  Perhaps some way to make iframes not seem like iframes to the pages they load?

Thanks.