You can look at this extension:

• searchhotkeys: http://nic-nac-project.de/~kaosmos/index-en.html#searchkeys

screenshot

I installed this extension, but I can not find where I should set the preference "extensions.searchhotkeys.disable_all" to true.

Type about:config in the location (address) bar and press the Enter key to open the about:config page like you open a website by typing the URL in the location bar.

• if you see a warning message then you can confirm that you want to access the about:config page.

See:

• http://kb.mozillazine.org/about:config

• use the Search bar at the top of the about:config page to locate preferences more easily
• preferences that have been modified and do not have the default value show as bold (user set)
• preferences that are user set (bold) can be reset to the default value via the right-click context menu
• preferences can be modified via Modify (String or Integer) or Toggle (Boolean) in the right-click context menu and by double-clicking the line with the pref
• preferences can be created via the right-click context menu: New -> String, Integer, Boolean

Thanks a lot! I finally disabled this bar.

You're welcome