One change in Firefox 4 is to by default stop Firefox displaying the warning message, but it can be turned back on by changing some preferences.

1. Type about:config into the location bar and press enter
2. Accept the warning message that appears, you will be taken to a list of preferences
3. Locate the preference browser.tabs.warnOnClose, if its value is set to false, double-click on it to change its value to true
4. Repeat this for these 3 preferences browser.warnOnQuit, browser.warnOnRestart and browser.showQuitWarning

There is a long thread discussing this https://support.mozilla.com/en-US/questions/780601?page=2#answer-146240

The short answer is that

• you probably will not loose the tabs, as the restore option may still exist
• if you want firefox to ask on closing change browser.showQuitWarning

I disagree with the rendered answer; you cannot work with assumption like 'you will probably not loose the tabs', etc. Those tabs mean information that you may never recover because sometimes it is part of several chained mental decisions as in search some info, get some answers, search more in-depth info, find other answers, do some mental inferences, search again, find more info, and repeat that during a whole day or more. Do you consider that just 'loosing some tabs'? I completely disagree.

I have a more through presentation of why loosing the "Save All Tabs" functionality is not addressed by the above tricks here: https://support.mozilla.com/en-US/kb/ask/discuss/616#post-940

Session restore works more reliable if you choose Firefox (Tools) > Options > General > Startup: "When Firefox Starts": "Show my windows and tabs from last time" instead of relying on the Save & Quit dialog.

I am not talking about Save & Quit, I am talking about Bookmarks -> Bookmark All Tabs, an EXTREMELY USEFUL functionality.

I do not care about "Show my windows and tabs from last time", this will work only if you are not using a Private Browsing session (which you may have forgotten you had started) and how about if you have several windows totalling 350-400 tabs?

IF I AM USING NON-PRIVATE BROWSING I have another solution: crash the process in the task manager or shutdown / restart the computer without closing FF and next time FF will restore the session.

WHAT YOU DO NOT UNDERSTAND SO FAR IS THAT SOME OF US DO NOT WANT TO CLOSE THE TABS EVEN AFTER REPEATED FIREFOX RESTARTS.

WE JUST WANT TO SAVE OUR TABS USING THE "BOOKMARK ALL TABS" FUNCTIONALITY, OR THEY WILL KEEP ACCUMULATE!

WHAT IS IT SO HARD TO UNDERSTAND THAT WE DO NOT WANT TO CLOSE TABS WE JUST WANT TO SAVE THEM AS BOOKMARKS (NOT ONLY IN THE RESTORE POINT) BEFORE WE CONTINUE?

"Bookmark All Tabs" no longer shows in the Bookmarks menu unless you open the Bookmarks menu via the keyboard (Alt + B).

"Bookmark All Tabs" can be accessed via the right-click context menu of a tab on the tab bar.

You can make that menu item to show always this way:

Add code to userChrome.css below the @namespace line.

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

/* Always show "Bookmark All Tabs" in Bookmarks menu */
#menu_bookmarkAllTabs { display: -moz-box !important; }

To make all hidden menu entries visible you can use this code:

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

/* Always show all hidden menu entries */
#navigator-toolbox menuitem[class="show-only-for-keyboard"] { display:-moz-box !important; }

See also:

• http://kb.mozillazine.org/Editing_configuration

Hi cor-el, thanks for the info. I still don't know why you buried that option but I am ok using it with a shortcut after reading about it.

@mmarchid
Maybe now you see the advantage of asking in the Support Forum, rather than on an edit discussion, your questions are more likely to be seen and answered when you post here.

Cor-el ... it's B-rad ... wanted to thank you for this post. So so simple -- ALT+B and back in business to "Bookmark All Tabs" .... I like short and simple, thank you !

I agree that this feature shouldn't have been hidden. I frequently use it - you're researching a product, you have 17 tabs going -- you don't want to lose all your work -- "Bookmark All Tabs" --- come back later. How sweet is that ? You have 8 blogs you like to read daily - "Bookmark All Tabs", then every day, Open All Tabs -- beautiful. This should be an upfront feature, not something pushed to the background.

Thanks also for the more detailed "how to" to make it permanent ! Above and beyond ! Cor-el - Any relation to Kal-El or Jor-El ? Super advice !

Thank you! I'm still getting used to Firefox 4. It seems much more complicated to find answers to common problems - it seems to me that restoring tabs on restart would be a no-brainer, and you sho.uld have to opt out of it if you didn't want it, rather than the other way around.

I followed your easy instructions, and assume they will work.

Thanks again.

many thanks for making it so easy to understand...