someone else started by replacing browserd and some of the interface packages. i did start looking into this a while ago but due to some issues @ home it had to go on hold.

microb is split into several components with a mix of licenses. the ui as stated is closed and the microb-engine is open. in the middle is one of the eal pacakges iirc. this package had an open replacement by the same guy as browserd, it was a requirement, but the original may have been updated on the garage page.

what had previously been talked about therefore was to keep existing ui and replace the backend. microb-engine provides the gecko/xulrunner parts so that was what i was looking at.

the garage site contains all the patches and a copy of the xulrunner versions they are applied to. not sure if this was updated recently as well to match installed version, haven't had chance to check. some if the patches are trivial, just branding changes. the rest are performance, gstreamer and modify the dialogs, notifications etc to use hildon gtk.

The patches won't apply cleanly to the newer versions. If you examine the code and the patch it is usually quite simple to spot the required changes, a nested if here, a renamed variable there.

As pali found with fennec, there was a javascript change around v8/9 iirc, which may cause more headaches. even updating to v7 or 8 would be nice though as it would support newer adblock.

finally, gst patches if not yet merged upstream are in the mozilla mailing lists.