Compatibility broken with nightly 21? Rated 5 out of 5 stars

With Firefox Nightly 21.0a1 (2013-02-03) I don't see the group tabs, only a line with a "+", "hibernate group" and "-". Is the compatibility broken?If so, may someone suggest an analogous extension (groups, hibernated groups, tabs not getting loaded upon session restore (the most important feature for me)).In Firefox 18 the group tabs are there, but the whole browser works way slower, almost unusable.

One Ken Thomas, could you look into this?

Strange behaviour with Tab Mix Plus Rated 4 out of 5 stars

Awesome add-on, but together with Tab Mix Plus (at least I think that's the problem) it handles tabs very strangely.
When opening a new tab in a multi-row group, new tab is opened in place of an active tab and the active tab (and everything to the left of it) is shifted to the left.
When opening multiple tabs by middle-clicking links they open in the "wrong" order - 3, 2, 1. Should I disable "change order" in TabMixPlus?
When moving tabs between groups, displayed tab rows "jump" a couple of rows down or even to the end.
Also, couple of times the width of tabs changed and then changed back after some time.
All of this makes tidying up over 600 tabs (well, I'm closing the majority of them, but still) wery uncomfortable.

I'm guessing, the problem is that TabGrops Manager has "hardwired" tab handling which conflicts with the custom tab handling options of TabMixPlus, but I didn't find anyone reporting the same problem.
Maybe it's a version conflict? I use FF 7.0.1 under Arch Linux (64-bit), TMP 1.3.8.7.pre110917a and TGM 2011.10.9.1.

If TGM does have hardwired custom tab handling, maybe there should be an option to turn it off

(Cross-posted to the TGM bug tracker)

This review is for a previous version of the add-on (2011.10.9.1.1-signed.1-signed).