Make your extension compatible with SeaMonkey, if you can

Extensions are great. They’re one of the technical reasons (the Manifesto comes first, of course) that make us choose Firefox, and they usually help us to save the day.

Firefox is Mozilla main and most used product, and of course if you want to create an extension Firefox is your main target. But why limit yourself to Firefox?
You may not know it, but if your extension isn’t too complex, and it doesn’t rely on Firefox-specific technologies, it will probably be compatible with SeaMonkey out of the box, all you have to do is to register SeaMonkey in the install.rdf file, with this code:

<em:targetApplication>
  <RDF:Description>
    <em:id>{92650c4d-4b8e-4d2a-b7eb-24ecf4f6b63a}</em:id>
    <em:minVersion>min version</em:minVersion>
    <em:maxVersion>max version</em:maxVersion>
  </RDF:Description>
</em:targetApplication>

so that all of the SeaMonkey users can benefit from your extension, installing it painlessly and receiving the automatic updates from a.m.o. With the rapid release process is even easier, because the gecko version on Firefox and SeaMonkey is strictly related, so you can discover easily which are the correct min and max version numbers.
Everything you have to do is to loose 5 minutes of your time to try your extension on SeaMonkey, that’s all.

Not all of the extensions work out of the box, though. I’m not an extension developer and I don’t know anything about xul or js (so don’t ask me for help), but I’ve discovered that in some cases the compatibility with SeaMonkey is just one line of code far.
If you have to register some component (e.g. a stylesheet) in chrome.manifest and you have a line similar to this:

style chrome://browser/content/browser.xul chrome://myext/skin/mystyle.css

everything you have to do to make it compatible with SeaMonkey is to add this other line in the same file:

style chrome://navigator/content/navigator.xul chrome://myext/skin/mystyle.css

this is the case of extensions like xclear, Reader and Readability.

In some cases this is not enough, and then I don’t know how to help you, but I want to ask you all, extension developers, to spend these 5 minutes to install SeaMonkey and check these two easy things.

In this way we’ll all win: SeaMonkey users will be able to benefit the functions of your extension, and you’ll get hundreds of possible new users.