Once again the design completely ignores people who use small screens or who use a window interface :(
This is the new MSO at 816px (on my system, YMMV), with the left sidebar disabled:
This is a bit too narrow for me though. I'd rather have a window that's half the width of my monitor, which on the machine I'm posting on right now is 1920. But widen the window to 817px and beyond, and it breaks down (or breaks up?):
WHY???
I'm not even sure whether the narrow-screen behavior is intended or not. I guess an accommodation for mobile devices? Please keep it! Please, please keep it!
And please make the right side-bar collapsible, like the left side-bar is**. This shouldn't be a preference, it should be a button that you click (with a discoverable keyboard shortcut, of course).
By the way, collapsing the left sidebar shouldn't be a user preference. Its desirability depends on the window width, so it should be possible to toggle it on a window by window basis. I think a decent compromise would be to make it a hidden preference that you can quickly toggle on the page, possibly a cookie-based rather than account-based preference since optimum window size tends to be device-dependent.