From the article from mozillazine.org:
mozilla.org today released upgrades to both Firefox 0.9 (0.9.1) and
Thunderbird 0.7 (0.7.1) to fix some minor bugs present in both
releases. Both releases correct some flaws in the extension system
that some users may have been experiencing, as well as a new icon set
for the navigation toolbar on Windows and Linux in Firefox 0.9.1. All
users of both products should get this upgrade.
