I suspect there are few of hot pixels on my panel. As it is still under warranty and by the rules of my vendor I can replace a machine if panel has a 3 dead pixels on it, I'd like to check how many dead pixels there actually are. In Windows, there are plenty of simple applications that just fill the whole screen with different colors so hot/dead pixels are easily visible. Does something like this exists for Ubuntu?
You could use
Then open them in
Then dual click on the picture to get it full screen.
Following is a How-To for the visual learners.