Window close buttons small / hard to close using touch device
Display the Inspector.
Use your finger to click on the X to close the inspector.
Result: It does not close , ever, under any circumstances.
Use the mouse to close the inspector.
Result , it does close, but at the piano I don't have a mouse.
If you are using a touch screen, you just can't close the inspector because the x sensitive region is too small for the resolution of touch sensitivity on Windows computers.