I got a couple patches through to Firefox proper. One was a fairly easy bugfix[1], but the other[2] took me lots and lots of iterations to get correct. The mentor was extremely patient, taking what I think was more time to explain to me how to do it right than it would have taken him/her to just do it themselves.
The worst part for me wasn't understanding the code (though following through some of the XPCOM stuff is tough), but working with Mercurial. I was tempted several times to abandon it and use a git mirror. Anyone that says patch queues are equivalent to git rebase is crazy.
If you dont need to actually push the code to the reposity (which you wont for the first bunch of patches) it is totally fine to use git, the github mirror is at
The worst part for me wasn't understanding the code (though following through some of the XPCOM stuff is tough), but working with Mercurial. I was tempted several times to abandon it and use a git mirror. Anyone that says patch queues are equivalent to git rebase is crazy.
[1] https://bugzilla.mozilla.org/show_bug.cgi?id=1006656 [2] https://bugzilla.mozilla.org/show_bug.cgi?id=907310