I'm developing a VR app using the MRTK and Unity. I tried initially with UWP but its limitations are to wide (Microsoft, please do something!) and decided to do it with Steam.
All is working fine when I compile and run the application outside Unity except I get a mirror window on my desktop displaying what's running in VR. I find it really annoying and useless but can't find how to get rid of it. Is it a setting in Steam itself, in Unity or is it something controlled by compilation settings?