How to detect which screen /display user clicked on?

[ilbarbax]

and second questioin...how to determine the relative mouse position on the selected screen?

I have 4.7 version.

Thanks

[airsoftsoftwair]

What exactly do you mean by "screen"? A Hollywood display? Then you can simply install an event handler using InstallEventHandler(). The message you get in your callback function will contain the ID of the display that received the event.