Safari's "You have entered text on..." when closing tab/window

[jollino]

Hello all,
I recently started using Mountain Lion after upgrading from a 2006 iMac to a 2012 Mac Mini. Everything's smooth and nice, except that I can't seem to get rid of the annoying "You have entered text on “[page title]”. If you close the tab, your changes will be lost. Do you want to close the tab anyway?" warning. I had gotten rid of it somehow on Lion, but the DebugConfirmTossingUnsubmittedFormText default doesn't seem to work.

I tried both

defaults write com.apple.Safari DebugConfirmTossingUnsubmittedFormText 0

and

defaults write com.apple.Safari DebugConfirmTossingUnsubmittedFormText NO

to no avail. Made sure I quit Safari before doing so, no difference. I used 'read' to make sure that it was set to 0 or NO, and it is. The warning still appears, though.

Can anyone point me towards what I'm missing? I'm sure it's something stupid, but I can't for the life of me figure it out.

Thanks!