I don't think platform guidelines that anyone listens to have been a real thing for a long time. Even between apps released by MS there is little or no consistency at times, things that should be part of standard OS provided chrome like title-bars are a random mess - good luck guessing what has input focus sometimes, particularly with multiple monitors, as you unlock or switch vdesktop, without clicking to make sure.

I keep thinking of writing something that detects the top-most app window and draws an obvious box around it.