Comment 3 for bug 579091

I can confirm this one.
Opening new Firefox windows or restarting the program (e.g. after installing/updating addons)
will cause custom controls to disappear (in the newly opened window).
This will only happen with the Ubuntu Firefox Modifications 0.9rc2 enabled. All is fine when it is disabled.

I could reproduce this with the Adblock Plus icon in the toolbar or simply by adding a "Open in new tab"
button to the toolbar, both will be vanished in the new window.

The same thing happened in Ubuntu 9.10, too.
Current system:
Ubuntu 10.04
Firefox 3.6.3
LANG=en_US.UTF-8