Comment 167 for bug 255263

Túlio:
If you look at how addons are made, I really really doubt they could stop them. Firefox is written, in large part, entirely in Javascript. The addons have to have access to Chrome to be able to even put a button on a toolbar or an entry in a menu. If they have access to Chrome through Javascript, they've got access to all of it. To block it would be like....telling Greasemonkey "you can modify this website in Javascript, but *not* the navigation bar"