[kevincox]

It would be nice to be able pop-out a window (and set pop-out to the default) so that I can use the proper window manager built into my OS.

I don't think having an in-tab window manager is a bad idea. There are numerous sites that I like to keep contained in one tab, however for the heavy-interactive types of site where windows like this make the most sense I would generally rather use OS windows so that I get keyboard shortcuts, tiling, multi-monitor, snapping, always on top and all of the other features that exist in my OS.

[swiley]

Wasn't this how windows originally did tabs?

[noisem4ker]

Certain programs, yes. Notably earlier Opera versions and several image editors.

It's called Multi-Document Interface (MDI). https://en.wikipedia.org/wiki/Multiple-document_interface