Is there a way to make Android believe the current device has a certain screen size (pixels, not density) which is smaller than the actual display size (again pixels, not density)?

I need the following: On a device (not emulator) with a 1280x720 pixel (for example) display I want to use only 800x480 pixels - resulting in a homescreen attached to one of the corners and the rest of the display left black (or whatever color).

This has nothing to do with screen resolution since changing the resolution would fill the complete screen - which is what I don't want (see above).

Similar questions on SO have not been answered with any help.