# SDL_MainThreadCallback Callback run on the main thread. ## Header File Defined in [<SDL3/SDL_init.h>](https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_init.h) ## Syntax ```c typedef void (SDLCALL *SDL_MainThreadCallback)(void *userdata); ``` ## Function Parameters | | | | ------------ | --------------------------------------------------------- | | **userdata** | an app-controlled pointer that is passed to the callback. | ## Version This datatype is available since SDL 3.2.0. ## See Also - [SDL_RunOnMainThread](SDL_RunOnMainThread) ---- [CategoryAPI](CategoryAPI), [CategoryAPIDatatype](CategoryAPIDatatype), [CategoryInit](CategoryInit)