These are the various supported windowing subsystems
Defined in SDL_syswm.h
typedef enum SDL_SYSWM_TYPE
{
SDL_SYSWM_UNKNOWN,
SDL_SYSWM_WINDOWS,
SDL_SYSWM_X11,
SDL_SYSWM_DIRECTFB,
SDL_SYSWM_COCOA,
SDL_SYSWM_UIKIT,
SDL_SYSWM_WAYLAND,/* no longer available, left for API/ABI compatibility. Remove in 2.1! */
SDL_SYSWM_MIR,
SDL_SYSWM_WINRT,
SDL_SYSWM_ANDROID,
SDL_SYSWM_VIVANTE,
SDL_SYSWM_OS2,
SDL_SYSWM_HAIKU,
SDL_SYSWM_KMSDRM,
SDL_SYSWM_RISCOS } SDL_SYSWM_TYPE;