Posting the firefox extensions yesterday reminded me of a cool little trick for getting older extensions to work on newer versions of FF.

It doesn't happen very often, and sometimes there is a good reason for it, so try this at your own risk. All the same.. occasionally you'll come across an extension that hasn't been updated in a while, and quite a lot of the time it wont install due to discrepancies in the version number.

The fix? Just change the highest version number in the extension! the .xpi files extensions are packaged in are just .zip files in reality. Download the .xpi somewhere (right click -> save as), rename the extension to .zip and open it up. Extract the file install.rdf, and open it in a text editor - look for the line <em:maxVersion>X.XX</em:maxVersion> near the top. Change this to reflect the current version of firefox you're using.

To install, all you need to do add the install.rdf file back into the zip, and rename it back to .xpi - then install as per normal!