The 'smear' function is the only reason I keep Photoshop installed;
I would love to see a similar function integrated into Paint.net.
It is extremely useful when e.g. posting screenshots, but wnating to blur
out any personal data, or when ordering computer parts and wanting to alert
the shop of your payment (by just attaching a small jp. or png file with a screenshot
of the payment while blurring out all the other data from your web-based
online banking system).