Thanks--very useful Rated 5 out of 5 stars

Having an option to set the background color/image would be nice. I use a persona and glass about:blank so the repeat for the persona header looks a little "weird"; but I created this style (for Stylish) to take care of it (color matched for my persona):
/* Fx4: bg for Vertical Toolbar
**/
@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);
#vertical-toolbar {
/* use one color: * /
background-color: #7583F0 !important;
/* or use a gradient: */
background: -moz-linear-gradient(right, #7F7F7F, #171717) !important;
/*.*/
}
/* to turn off "Personas compatibility" (make it not "tile") */
#main-window:-moz-lwtheme { background-repeat: no-repeat !important; }
/*.*/

This review is for a previous version of the add-on (0.2.1).