That blurred display video is amazingly useful. It happens on all devices and happens when nothing is redrawn on a device. This means that it reuses incorrect output (it uses last output to add some effects but it should mix two). I still don't know why this happens but what's worse, I can't repro it. I will be investigating it. If I won't be able to find anything, there is still one thing I can do, redraw every display when it is visible.