What type of "add-on"??
Extension? or a plug-in?

The easiest would probably be an extension which is hidden from the user in the Addons Manager Tab > Extensions panel.

If you add this code to a userChrome.css file that you create and put that css file in a newly created \chrome\ folder in the Profile folder, it will hide that extension in the Addons Manager tab.

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */
#addons-page richlistitem[value="<-extension_id->"] {display:none!important;}

http://kb.mozillazine.org/UserChrome.css

You would also have to disable the Firefox SafeMode, which can be opened from the keyboard or the Run command line. SafeMode is a troubleshooting mode which disables extensions.

Take a look around the archives of this weblog.
http://mike.kaply.com/category/mozilla/
http://mike.kaply.com/2013/05/16/disabling-safe-mode-again/#more-1856

Another thing to consider is a user being able to use Firefox Portable on a USB stick. In a situation like that you would be better off with an operating system level "parental control" or monitoring program, rather than using something within a particular web browser.

No, you can't reliably prevent someone from disabling an extension.
It would be sufficient to start Firefox in Safe Mode (i.e. hold down Shift when starting).

See also:

• https://mike.kaply.com/2013/02/11/add-ons-in-the-distribution-directory/
• https://mike.kaply.com/2012/02/09/integrating-add-ons-into-firefox/

Search for child protect programs. Some will prevent the computer from going to 'wrong' sites. There are also programs that will record the computers activity.

Hi All,

I would like the add-on to be visible so that the child knows that he/she is being monitored. Could you suggest a way to re-enable the add-on if the child manages to disable it using the Add-On Manager tab.

I found that modifying the extensions.sqlite DB in the profiles folder solves the issue, but when I attempt it, i do re-enable the extension, but I lose the icon of my extension.

Hi All,

I think i found a way to achieve this perfectly by modifying the extensions.sqlite in the profile folder by running the sql query

"update addon set active=1,userDisabled=0,iconURL= where id='myid'"

However, the issue is that before i can modify the db, firefox restarts. Only after another restart, my code block works.

My question now is: Is there a way to delay the restart of firefox so that i modify the db before the restart occurs.