I made an addon for Firefox and it works with the latest version. My problem is that I want it to work with all versions of Firefox. How can I do this?
Add-on SDK 1.14 (the current release) marks add-ons compatible with Firefox 19 and disallows installation in older Firefox versions. If you don't like that you have several options:
app-extension/install.rdfin your Add-on SDK install and set
minVersionto something other than Firefox 19. If your extension is simple you might even get away with that and your extension will actually work in older Firefox versions, maybe even in Firefox 4 (definitely not below that however, restartless extensions were introduced in Firefox 4). This is obviously not supported and verifying that everything really works correctly (e.g. no memory leaks) will be close to impossible.
The main question is however: why do you want that? The current Extended Support Release is Firefox 18, so no version below Firefox 18 is supported by Mozilla. There are of course a few users on outdated Firefox versions for some reason but people who don't update also rarely go install new extensions. So, do you really want to spend tons of time making your extension work in Firefox 1.0 (release 2004)? How about Firefox 4 (released 2011)? How much effort do you want to invest into staying compatible with old versions when there are tons of addon-relevant changes in each single release?