Love this extension Rated 5 out of 5 stars
I've been using it for a long time in Ubuntu. However, there appears to be a problem with Gnome 3, Unity or gnome-shell, and Hide-Caption-Titlebar-Plus 2.60. If you reduce a window...then maximize it...all of Firefox's buttons become non-functional (example>Bookmarks) until you click the "Restore" button (to the left of the "Close" button). After that everything's fine until you reduce the window again.
BTW, under Gnome Fallback (gnome-session-fallback) there is absolutely no problem.
Thanks for a great extension.