This just happened out of nowhere and it gets worse over time and I don't know why this is happening. My monitor is 3 years old or so. I hope someone can tell me what that is .
ah, just figured that was part of the window's "tray".
if it is always present no matter what's being displayed than it is just a malfunctioned panel.
a lot of the better monitors come with a 3 year warranty. check it quick and hopefully are still in time to get it repaired\replaced.