Rated 5 out of 5 stars

As LijuC pointed out, on windows systems it's not enough to only change maxVersion tag. Also extension.cache file located in [user]\Application Data\Mozilla\Firefox\Profiles\[some-hash].default\ must be deleted(personally i would make backup first, just in case), to force firefox to reread version information and update status of extension compatibility.

This review is for a previous version of the add-on (1.4.3).