Rated 4 out of 5 stars

There is some development going on (at long last).
It seems that now new windows are created instead of the previous sub-windows. Thus creating multiple entries to Windows taskbar. And a lot of jumping windows when you dare to move the "split" or create a new split.
And the created splits are still not saved when Firefox is exited ...

Rated 5 out of 5 stars

>> Why the silence on FF4 update?!

The author of this splendid plugin is Japanese. Japan has - as you might know - been hit by severe earthquake and a big tsunami. Thus the author might have more important things to do than to update this plugin.

Rated 5 out of 5 stars

@yoyo08: you can reduce button size, and only make them appear if shift is pressed (appearance tab in Fox Splitter options)

Rated 5 out of 5 stars

After fixing the maxVersion in the install rdf, I got this to work partially in Firefox 4.01 (not in 4.0!) - it splits now, but unfortunately doesn't remember which panels were opened when Firefox is exited/restarted. It also seems to forget any other options changes ...
So for the time being I have to manually re-open all my panels each time I have to restart firefox ...
But at least I can open them ...