Comment 6 for bug 156090

Here's the steps I took to find this bug, launch Firefox, Tools, Addons, Get Ubuntu Addons, Select Adblock from the list. Install it. Now try and remove it through the Add/Remove Extensions window even after closing Firefox and the Add/Remove Extensions window and restarting Firefox.

This was done on the initial account created during Ubuntu setup, Firefox was launched via the Gnome menu, no commands or elevations (su, sudo, gksudo) were used. After installing the addon as a normal user I'd expect to be able to remove it as a normal user through Firefox's own addon controls instead of requiring an external uninstaller to be launched (in this case the Add/Remove... link in the Gnome Menu).