Review for Gmail Manager by BW Smith
Rated 1 out of 5 stars
Would probably be nice if it actually worked. Tells me it can't connect because my password is wrong (which it isn't wrong). I've seen comments where there's a workaround, but it's not worth the trouble to do the workaround when there are other add-ons that accomplish the same thing without the hassle.
To create your own collections, you must have a Mozilla Add-ons account.