Wow--I can't believe how long it took to implement this. It's basically docking functionality with the border layout. On this demo page you can drag the side panel to any side (top, left, bottom, right) and re-dock it: http://18.104.22.168/myDock/
I made this for myself, so if anyone has any interest in this sort of functionality let me know and I will decouple it and repackage it as an extension or plugin for release.
first of all, it looks nice. as a small improvement suggestion, i would make regions only moveable on klicking the titlebar and give it on hover another mouse-pointer to see, that you can do something.