Letterbox mouse coordinate interference

[KelvinShadewing]

When scaling a window so the aspect ratio no longer matches the game's, getting the mouse coordinates does not work properly anymore because the letterbox width/height changes the position of the game window. SDL2 appears to be getting mouse position from the top left of the window itself instead of the renderer.

[jfmherokiller]

https://stackoverflow.com/questions/26238701/sdl2-resizing-the-window-mouse-position