WORKAROUND WORKS! Rated 5 out of 5 stars

The workaround described by MT7523 (link several posts below) works like a charm for Red Cats (blue flavor). Finding a working download for the theme is a bit tricky (the developer's website is totally down), but with a bit of poking around, it turned up. The instructions are easy, and it worked.

One note, I completely UNinstalled the Red Cats theme from FF13 before upgrading to FF14, and THEN installed from the adjusted .jar file on my desktop. And voila! The kitties were back. MUCH appreciated, as FF isn't FF without Red Cats (blue)

This review is for a previous version of the add-on (5.5.2).  This user has other reviews of this add-on.