Now with kinda SeaMonkey support... Rated 5 out of 5 stars

Sadly, new version 0.4.2 is still not SeaMonkey compatible. :-(

Update: OK. Got it running. You can get the howto here: http://code.google.com/p/gt-tasks-sync/issues/detail?id=30

I recommend using 7-Zip for extracting install.rdf and Notepad++ for the manual modifications.

Great job, Thomasz! Thanks an awful lot for this add-on!

May I suggest an improvement? I would like being able to move the list items, just as we can do it on the google website.

@Thomasz. You wrote: > use the drop-down menu near the sync button.

Well, this produces a sandglass for about 2,5 s. That's it. Whatever I try to rearrange the tasks before, in the meanwhile, and afterwards doesn't show any effect. Clicking, dragging, dropping, double-clicking, or even shouting at them - no reaction whatsoever. Oh wait; clicking and double-clicking opens the task's details. But no rearrangement. At least not in SeaMonkey's Lightning. :-(

This review is for a previous version of the add-on (0.4.1).  This user has other reviews of this add-on.

If you mean rearranging the tasks, then that's already possible, use the drop-down menu near the sync button.