You already can with X11, for example running your rogue graphical program inside a graphical virtual machine. The vm gui will filter-out the events that happe

You already can with X11, for example running your rogue graphical program inside a graphical virtual machine. The vm gui will filter-out the events that happen outside the window and the rogue program will think it's running alone. It's nice that wayland makes such containerization much lighter, at least concerning the GUI (you still need to hide your filesystem, network, etc if you want to run rogue programs under wayland). But I don't see the point in enforcing it for each and every one of your programs. It's extremely unergonomic.