WIN32: High-DPI scaling on OpenGL-rendered games cause mouse DPI to scale down

[lotharsm]

I noticed a strange issue when testing TWP with the current master code.

To replicate, you need a High-DPI screen with the OpenGL auto-scaling enabled. I usually tend to set my mouse DPI fairly high to get a very "fast" movement.

I noticed that after starting TWP, the mouse curser moves _way_ slower than before, even after returning to launcher through the GMM.

I wasn't able to replicate it with the "default" OpenGL rendered games though, it seems to be an issue with the OpenGL3D backend.

Switching to and from the OpenGL3D backup seems to mess up the internal scaling somehow...