which contains the interesting quote in the comments "Most current XUL Runner apps that I know about (those that get mentioned on planet.mozilla.org) tend to have their own patches against XUL Runner that haven't yet made it into the core sources to fix issues specific to their app."
Which was my experience with the platform too.
It is true that I have missed that, but you'd need to cite another twenty or thirty projects of a similar size before you'd catch up to the hype. (And I'd still question whether Komodo actually gets anything out of being on Mozilla vs. QT. Cost/benefits analysis of things on the Mozilla platform tend to miss the opportunity costs of having started out on a better-but-more-humble framework in the first place.)
(And while I won't hammer on it too hard, it would be nice if the app that is putatively on the platform actually ran on the platform instead of a modified platform. I don't have to go patching QT or GTK every time I want to make an app. If someone knows that it runs on XULRunner, great, please say so. All my googling is getting is people saying how nice it would be.)
