Question

I just built a very simple add-on for Firefox, but it’s only compatible with FF 8+. I’d like to make a version that’s compatible with FF 3.6 and FF 4+. Is there an SDK for those versions I can use to create/compile a version that’ll work with those versions?

Answer 1

No, even Add-on SDK 1.0 marked the add-ons as only compatible with Firefox 4.0b7 and higher. The main reason is that Firefox 3.6 didn’t support installing add-ons without a restart and developing an add-on that will use the “conventional” approach in Firefox 3.6 and install without a restart in Firefox 4 and higher is pretty complicated. There are other issues with Firefox 3.6 as well. So your options are:

• Just ignore Firefox 3.6. This should be the best course of action given that this Firefox branch will become unsupported soon – its already low user count will be significantly reduced again.
• Create a classic extension, without using the SDK. This might be non-trivial depending on what your extension does, and you will most likely lose the ability to install without restart (as I said above, keeping it while being compatible with Firefox 3.6 is very non-trivial).
• Use a pre-release Add-on SDK version, e.g. Add-on SDK 0.9. The differences to current SDK versions might be insignificant enough for your extension to work but you should expect bugs and issues due to browser changes since this SDK was released (it lists Firefox 4.0b6 as maximal supported version).