Fixed! Fun fact: I had to DISABLE hiDPI support in SDL. Guess is bugged.
Are you sure you haven't forgot about multiplying the event coords by SDL_GetWindowPixelDensity?
SDL_GetWindowPixelDensity
Oooh! Didn't know about this. Neither SDL_GetGlobalMouseState nor SDL_MouseMotionEvent docs speak of no such thing. Anyways, it works now :P
