Extensions

XPCOM is, currently, a core Mozilla technology. Developers use XPCOM for a variety of reasons, many of which result in XPCOM components being accessed from JavaScript. XPCOM uses IDL to describe interfaces. This can make XPCOM components a bit rigid and not feel right in JavaScript. Recent support for optional parameters in IDL has helped a little. Another helpful concept is using JavaScript functions in place of an IDL callback interface. For example:

I’ve mentioned plugin monitoring, a student project from Seneca College, back when the developers sucessfully got their project “marks”. I am quite pleased to see the project actually land in Firefox 3 (Mozilla 1.9) last week (bug 412770).

Unfortunately, the js-ctypes project got back-burnered for a while. Fortunately, some great contributors swooped in and landed some really nice bits. Fredrik Larsson helped out on some Linux problems (bug 416119), filled in ANSI string support (bug 416229) and setup an xpcshell test framework (bug 427286).

Over the weekend, code landed to restrict the ability of web content to access “chrome://” resources (see bug 292789). This shouldn’t affect many extensions since the restrictions are focused on web content, not chrome content. However, if your extension injects content into the web content, you could be affected. An example can be found in bug 428848. Venkman can’t load venkman-source.css, a stylesheet that is injected into unprivileged, web content.

And making Firefox 3 ignore extension compatibility checking is wrong!

Firefox 3RC1 is just around the corner. Surprisingly, more than a few of the current Top 100 add-ons on AMO are not updated to work in Firefox 3. I say “current” because when Firefox 3 ships, those old add-ons will no longer be in the Top 100. Alex Polvi has a chart (updated daily) showing the status of Top 95% of AMO add-ons (by usage). You can see that many of the Top 100 have been updated to at least Firefox 3.0b3 or greater.

One of the new XMLHttpRequest features in Firefox was cross-site requests. It was based on an W3C specification and would have allowed web content to make cross-site XMLHttpRequests. I say “was” and “would” because that feature was removed in Firefox 3.0b5 due to security concerns and some specification changes too close to the Firefox 3 release.