Alt (option) 1 doesn't seem to do anything; I'm guessing that's the Windows equivalent of command-1. In the "View" menu, "Project Workspace" can be checked or unchecked and either way there's nothing there. (I've even tried quickly spamming command-1 on and off to see if I can see the flicker of a corner of a window somewhere.... nothing!)
edit: Alright, tried one last thing... and it worked! I had been trying to change the resolution with A:M open, and it didn't do anything useful as the UI seems to still maintain the same size of the original resolution (parts of it bleed onto the second monitor). However, when I changed to 800x600 with A:M closed and then opened it, I got the Workspace back! Whew!
After closing and re-opening A:M, it seems that the Workspace moves around on its own if it's not docked to anything. And if you don't move it back every time, eventually it winds up off-screen. Dunno if this has been fixed in a more recent version.
Thanks for your help tho!