Very unhappy to see that Firefox 13 is showing the contents of my HTTPS webmail and online banking sessions in it's "New Tab" thumbnail feature.
Secure content which you do not want made public (bank account numbers, email subjects) is captured and clearly readable in the large thumbnail images.
The little button to turn off the feature does not remove the cached images, only clearing recent history (Ctrl-Shift-Delete) will do that.
Dear Mozilla, please disable this feature for HTTPS pages?
Update: Woohoo! got a name check on The Register for this story :)
Firefox New Tabs security nightmare
Firefox New Tabs security nightmare