Rated 5 out of 5 stars

per oobidoobbanoobi el jul. 6, 2009 ·

for those who would like an experimental workaround for v3.5:

1)click 'ignore version check'
2)save the .xpi to your pc
3)open the .xpi with 7-zip and edit install.rdf
4)change the value after 'maxversion' from '3.1a1pre' to 3.5
5)save and exit notepad. 7-zip will ask if you want to update the archive, pick yes.

the .xpi file should install now. it's working for me, but i only use the 'duplicate in new window' feature. of course, DO THIS AT YOUR OWN RISK. thanks to Mattallyc for the idea.