I am often switching back and forth between native MacOS apps -- and apps running in a Parallels VM (usually Windows). When I have several layers of various apps open, it's momentarily confusing which is running in a VM -- and what is natively. Please provide for the ability to display any app's window frame (running within a Parallels VM, that is) -- in some OTHER (contrasting) color -- than that of native macOS's dark grey. It would add immeasurably to usuability in my view. A simple (if somewhat trivial) Example: if I run Word for Mac, then of course it has nothing to do with Parallels and will display as a standard MacOS app...BUT if I start up Word [for Windows] within my Parallels Windows VM - then it would be great if I have the constant visual reminder via that app's Title Bar being in, say BLUE or Parallels' Dark RED...