Use DirectDraw techology(or similar) to make window contents absolutely secure

[Proposer233]

When DWM is disabled,SetWindowDisplayAffinity won't work.For that,we can add a mechinasm.Use a DLL to inject into protected processes,and hook common functions in user32.dll.When processes try print contents into client area of its window,not do that actually,just pass it to the driver.
Use driver to register a display device driver,and show it in device surface level.

[DavidXanatos]

that would be beyond complicated and overkill, a isolated desktop should be good enough.

[Proposer233]

If some programs use techologies like DirectX,could it work?