A hint that specifies the address of another SDL_Window* (as a hex string formatted with "%p").
the address (as a string "%p") of the SDL_Window* that new windows created with SDL_CreateWindowFrom() should share a pixel format with
By default this hint is not set.
If this hint is set before SDL_CreateWindowFrom() and the SDL_Window* it is set to has SDL_WINDOW_OPENGL set (and running on WGL only, currently), then two things will occur on the newly created SDL_Window:
1. Its pixel format will be set to the same pixel format as this SDL_Window. This is needed for example when sharing an OpenGL context across multiple windows.
1. The flag SDL_WINDOW_OPENGL will be set on the new window so it can be used for OpenGL rendering.
This hint is available since SDL 2.0.2.