In my case, this error persists until Firefox 14.0.1. I tried with '-safe-mode', disabling languages, addons and plugins but I never got that dialogue displayed.
I found that this problem didn't occur with other profiles, so I created a new profile and imported all my data and preferences through Sync. Sync Firefox saves the day. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to firefox in Ubuntu. https://bugs.launchpad.net/bugs/994244 Title: Cannot clear recent history. Dialog is never displayed. Status in “firefox” package in Ubuntu: Confirmed Bug description: When I click on 'Clear recent history' from 'Tools' menu or 'Preferences -> Privacy' nothing happens, the dialog from which individual parts of private data may be cleared is never displayed. Firefox 12.0 (12.0+build1-0ubuntu0.10.04.1) on Ubuntu 10.04.4 (lucid) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/994244/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp

