Firefox 16.0.1 warns on closing multiple tabs but options set not to warn

Question

Firefox just updated itself to version 16.0.1. Now, when attempting to close multiple tabs, I get the "Confirm close" warning even though the "Warn me when closing multiple tabs" option is unchecked.
I tried checking that option, confirming the change, then unchecking that option again & confirming the 2nd change, too. This has made no difference. Firefox is not obeying the option setting.
The problem didn't occur before the update to 16.0.1 but did occur in the first session afterwards & has persisted since.

Answer 1

The more I encounter this piece of stupidity, the more annoying it gets. The assumption that '''no''' user knows what he/she is doing is one of the things that made Windows Vista such a disaster. Firefox shouldn't be copying failure. If Mozilla had time to cause this problem in version 16, it has no excuse for waiting until version 18 to undo the damage. It has time to reverse the change '''now'''.
There's a good argument for the warning option to be enabled by default. There's none whatever for making it compulsorily enabled, regardless of the user's wishes.
It is, of course, possible that someone will go into the options dialog, disable the warning option & then close multiple tabs by mistake. In that situation, it's the user's own fault. If it's too much trouble to undo the error, the user can re-enable the warning option & stop it happening again.
If there's unsaved data on one of the pages, that page ought to (& most will) warn the user that closing/leaving the page will lose the data. If there's no warning, it's the fault of the page code -- provided, of course, that the browser raises the relevant event when the tab is about to be closed. If the browser isn't raising that event for some reason (e.g., because the tab with the page isn't the active tab), '''that''' is the problem requiring attention.