Hacked bugzilla for fun for the first time in ages tonight, and javascript for the first time ever. Mostly successful, though sadly the javascript I used as the starting point (and which is 98% of the code ;) is GPL, which means it probably can’t see the light of day in bugzilla, which is MPL. Exactly what either of those mean in a web context being up for debate though, I suppose. Hopefully I can at least demo it for fun on b.g.o on Saturday morning, if I can work out the feature regression it is currently causing, and maybe someone more skilled than I in javascript/DOM can reimplement it clean room :) (I’ve emailed asking for permission to relicense to use in bugzilla, but I’m not holding my breath.)
By the way, I highly recommend the site I got the javascript from, if you want to play with DOM and javascript. The walkthroughs are very clear and the example code is very clean and well commented.