IDEA: Program to restrict utilized fraction of physical resolution

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I'm thinking of a program in which a border can be defined, for example from 100,100 to 924, 668. All display activity should be restricted to that area, then - resulting in a black, unused border around. This should work on a rather low level: In fact, the whole operating system and all running applications including 3D games should think that they're running at the lower resolution.

Thanks in advance for considering!