Do any RPTVs have an anti screen burn device?

As subject, and by device I'm thinking of something a buddy mentioned he had seen which was a moveable grey square that could be placed over parts of the screen with the remote - i.e. to cover any onscreen gfx or logos.

For my liking, a nice blurring box like those they stick over peoples' faces would be ideal.

Do any of the RPTV's on the market have anything like this?

I ask as I'm looking into a set for mainly Sky digital viewing and occasional console use - probably with brightness and contrast turned down.

(also, do RPTV's work with light guns such as Time Crisis, Point Blank et al?)

Many thanks