Title is self-explanatory. The game insists on being "always on top", no matter what combination of Windows keys you throw at it, or ingame options.

This needs to be fixed if you expect anyone to record or stream it.

(Copy from Steam thread)

I have had some luck in full screen. It overrides my desktop, but anything I have opened in my Windows bar, if I hover over and directly select, I can open. So when I have my browser to look at, Alt-Tab, hover over Chrome and when the small display window pops up, click on that directly.

Does this fix the problem? No, not at all. Does it help mitigate it? A tiny bit. Also you should probably post to Kalypso directly since this is a cross platform bug and not likely something Steam or GOG might be able to fix (since it is on both).