Move tab to new window not working

[bethel95]

Update: I just did a test where I disabled VT, restarted Firefox, and tried again. As expected, "Move tab to new window" is working fine then. Here's where it gets interesting: Re-enabling VT without a restart gets VT working again without breaking FF. Unfortunately, VT reverts to the light theme (I prefer dark), and switching themes doesn't work without another restart (the tab background goes dark, but the text stays red, so it's unusable). As soon as I do the restart, "Move tab to new window" is broken, again.

Original post: Starting about 3-4 weeks ago (possibly longer), all attempts to move the current tab to a new window (using either the context menu item or shortcut keys) fails. I am (and have been) using TabMixPlus, if that's a factor. This was working after I installed this extension back in early Dec.

I'm using FF 36.0 (just updated yesterday) on Windows 7 Pro x64 SP1.