Firefox 7 Successor Firefox 8 allows to restore tabs on demand, disables third-party add-ons by default, adds twitter as a search engine to the search bar and offers improved tab animations besides all that when you upgraded from Firefox 7 to 8 you’ll be presented one-time add-on selection dialog to to select the add-ons you wish to keep or disable, this will happen only once and not for each time when you start Firefox.
This is good for Firefox users protects from third-party malicious add-ons, even though there are legitimate cases where security software installs add-ons without user consent. If you’re a bit confused and you’d like to tackle third-party add-ons on your own and you don’t want to view the add-on selection dialog when upgraded from Firefox 7 to Firefox 8, here is how to disable it.
Disabling Firefox Add-on Selection dialog
1. Type about:config in address bar and proceed forward by agreeing to the warning.
2. Type or paste “extensions.shownSelectionUI” opposite to Filter, double-click the preference and turns its value to False.
This preference exists in Firefox 7.