From bug 1198627 comment 5: "what happens to keyboard events that aren't from arrow keys? F12, for example. They don't seem to bubble up to a listener that does anything with them."

The keyboard shortcuts available when the breadcrumb trail has focus seem to only be a subset of those in the markup pane, I don't think there's any additional shortcuts. Can I suggest removing keyboard focus from the breadcrumb trail entirely; and having everything bubble up to the markup pane? I think the behaviour will be the same.

I fixed this in bug 1264907. Now all key events (except left/right arrows) bubble up, so all keyboard shortcuts should still work.