Application in windowed mode - Why does finger-touch work with Unity4x and no longer with Unity5x?

I built under Unity4xx a standalone application in windowed mode, which runs under Windows7-Windows10 without any problems. Means, I can minimize, maximize and close the window with mouse as well as with finger-touch (on touchscreen) with help of the usual symbols (right upper corner).

When I do the same under Unity5xx then I can minimize, maximize and close the window with mouse only, no longer with finger-touch.

Why does finger-touch work with Unity4xx version and no longer with Unity5xx version?

Your response on this problem and a solution will be highly appreciated .

Thank you.