One Window Twitter

I love the improvements to the new Twitter for Mac app. As much as I love the new "Open in New Window" feature, I wish there was an option to keep all of the panels in one window. Something like what I've shown here (view attachment).

I know other apps do it this way and part of the beauty of Twitter for Mac is the more simple approach, but personally I think giving an option like this would be awesome. Maybe an "add panel to window" option or something like that...

Just a thought...