DESCRIPTION

The system window manager event contains a pointer to system-specific information about unknown window manager events. If you enable this event using SDL_EventState(), it will be generated whenever unhandled events are received from the window manager. This can be used, for example, to implement cut-and-paste in your application.

typedef struct {
         Uint8 type;   /* Always SDL_SysWM */
 } SDL_SysWMEvent;

 If you want to obtain system-specific information about the window manager, you can fill the version member of a SDL_SysWMinfo structure (details can be found in SDL_syswm.h, which must be included) using the SDL_VERSION() macro found in SDL_version.h, and pass it to the function: 

int SDL_GetWMInfo(SDL_SysWMinfo *info);