I often like to switch between an uncluttered super clean interface (just the writing area) and the full interface. The only way I see doing it right now is to press CMD+1, CMD+0, S+CMD+T, OPT+CMD+T (and whatever shortcut you want to assign to show/hide action bar), and then resizing a bit the window manually.
Honestly I would really love if that was just one click, one shortcut.
I ended up using Keyboard Maestro for that, but wouldn’t it be nice if it was built in?