You want to try Firefox 3.5 but your favourite extensions are not compatible with the new version? There is a possible solution for this problem.
As in case of extension interface nothing much changed between Firefox 3.0.* and 3.5, it is possible that extension compatible with older version will work without any changes – except the maxVersion setting, which prevents Firefox from installing apparently incompatible extension. Manually, you’d have to download XPI file, decompress, edit settings, re-compress, and install from file. Quite cumbersome, but…
Extension MR Tech Toolkit allows you to tweak some of the extensions’ settings, including maxVersion, without any hassle. Just right-click on an incompatible extension, select “Make compatible” from the menu, and that’s it! After Firefox restarts, if extension really is compatible, it will be working fine.