EDIT: My code for this is actually open source, if anyone would be able to look and comment.

Things I can think of that might be an issue: using a custom font, using bright green, updating the label too fast?

The repo is: https://github.com/andrewljohnson/StopWatch-of-Gaia

The class for the time label: https://github.com/andrewljohnson/StopWatch-of-Gaia/blob/master/src/SWPTimeLabel.m

The class that runs the timer to update the label: https://github.com/andrewljohnson/StopWatch-of-Gaia/blob/master/src/SWPViewController.m

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My StopWatch app reportedly screen burns a number of iPads, for temporary periods. Does anyone have a suggestion about how I might prevent this screen persistence? Some known workaround to blank the pixels occasionally?

I get emails all the time about it, and you can see numerous reviews here: http://itunes.apple.com/us/app/stopwatch+-timer-for-gym-kitchen/id518178439?mt=8

Apple can not advise me. I sent an email to appreview, and I was told to file a technical support request (DTS). When I filled the DTS, they told me it was not a code issue, and when I further asked for help from DTS, a "senior manager" told me that this was not an issue Apple knew about. He further advised me to file a bug with the Apple Radar bug tracker if I considered it to be a real issue.

I filed the Radar bug a few weeks ago, but it has not been acknowledged. Updated radar link for Apple employees, per commenter's notes rdar://12173447