Disable "Remove" items for options from default branch
(cant't be removed: we use clearUserPref() to remove)
(#3)
Middle-click to remove items
(#3)
Force update Apply button after double click and middle-click
(we don't check clicks automatically)
(#3)
Correctly detect changes in Firefox 3.0 and older:
uneval({ p: 0, __proto__: null }) // "null"
(#3)