in reply to Jonathan

Do you want screen curtain for specific programs OR temporarily since you are working late at night? Reading download.nvaccess.org/document… - if you press NVDA+control+escape once it will enable screen curtain until you restart NVDA (so, for this instance). If you press it twice quickly, it will enable it until you turn it off (so it will still have screen curtain on when you turn the PC and NVDA back on tomorrow for instance).
in reply to NV Access

@NVAccess Hi, thanks for the info. What I was talking about, and sorry for not formulating it more clear in the 1st post, was something like enable screen courtain for a specific display. I'm sitting at a docking station having 3 displays attached (including the Laptop) I'd like to only courtain the Laptop screen, for example. Hope that made it more clear.
I'd then, for instance, move my browser to that Screen/Display using Win+Arrows.