I remember hacking through the xml of the xulrunner and being able to
make hotkeys like ctrl-j for getting to the downloads popup. I think
any hotkeys like that should be able to be carried over from firefox
unless there's some limitation there for non-firefox instances of the
engine, which I don't think is there.
When I looked at adding ctrl-j for downloads, it looked like any
hotkeys that are in there don't come free from firefox, they have to
be enabled. The functionality is there, but the hotkey support may or
may not be in there.
Zoltan67, if you're willing to build it from scratch, I believe the
xulrunner config files can be configured to do that.
Otherwise, since Matt's changing the way it's structured underneath,
you could also just hold off for that.
Jeremy