Still the Best Rated 5 out of 5 stars
I have had no problems with ColorfulTabs co-existing with Tab Mix Plus in FF. Both of these extensions are proven to work on the Win2000 and XP platforms.
However, I have stopped upgrading Colorful Tabs since version 1.9. The reason is one of cosmetics. Versions higher than 1.9 has a brownish background on the tab bar which makes it really ugly on my Fusion Alternative Theme. Also, this background color spills over to the FF main browsing window.