The tabs get screwed up Rated 1 out of 5 stars
Installed it, see the icon, pressed it, it just opened a new window on the right side and adjusting the main window on the left side.
And then when clicked on that icon again, every tabs I'd all got screwed up and opened in its own separate tiny/micro sized window. Using Firefox 14.0
Do not use it. Its horrible and you will loose your tabs history as I did.
I couldn't see such a problem on my environments: Firefox 14.0.1 on Windows Vista and Ubuntu 12.04. Do you use any other addon which can conflict with multiple windows managed by Fox Splitter?