I'm afraid... Rated 4 out of 5 stars

...I'm past the limits of my knowledge. [isn't a frame address merely an extension of a frameset address?] Anyway, I wish you the best of luck, and thanks for your efforts. It would be boring if it was too easy! If there's anything I can do to help, just reply here.

This review is for a previous version of the add-on (initial.rev362.1-signed.1-signed).  This user has 4 previous reviews of this add-on.

A solution may be just around the corner

Dave Townsend seems to have discovered that the Prostetnic Highlighter words on the History World page in some user profiles.https://bugzilla.mozilla.org/show_bug.cgi?id=769709#c15Update 2013-05-24: It works for me now.