There's another "feature" which I rarely hit, and I don't even know how I did, what it's called or for, but when it happens, a draggable divider shows up in the middle of the screen, all my windows get "crushed" on the left side, and the right side is a dark blue/purple blank. I can drag the divider to restore the desktop, but it seriously angers me since none of my windows' original positions nor sizes get restored. Unfortunately, I have no idea how to disable it either. I believe it appeared starting with Win8, as I never saw it in earlier versions.