Which applications and which windows of these applications in particular are affected? When exactly does the window appear? Does it remain on its original desktop as well?

Ghm, I set this to 'Do nothing', but sometimes active window moved to current desktop

Oh, sorry. I thought that checks all options... Many thanks!

Settings -> Plugins and Extras -> Behavior of windows on other desktops.

Hello.
Situation: I use two virtual desktops, first is main and second that is only for one some program. This program sometimes activate its windows at the top.
Problem: if I am in the main desktop and program from another desktop turn his window to active state I see this window in the main desktop. Is there any way prevent that?
Thanks.