I'm using Windows 10, and I will frequently see a grey number on my screen. It looks like this 
It's not always on the taskbar. I've seen it other places on my screen. I'm pretty sure it's always the number 5, although I'm not entirely sure about that. I can't seem to interact with it at all.
Using Process Explorer, I've identified the program generating the icon as Visual Studio 2015. Closing Visual Studio makes the icon go away, although opening it back up doesn't immediately bring it back.
Does anyone know what this is, or what part of Visual Studio is generating it?