# SDL_X11EventHook A callback to be used with [SDL_SetX11EventHook](SDL_SetX11EventHook). ## Header File Defined in [](https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_system.h) ## Syntax ```c typedef bool (SDLCALL *SDL_X11EventHook)(void *userdata, XEvent *xevent); ``` ## Function Parameters | | | | ------------ | ------------------------------------------------------------------------------- | | **userdata** | the app-defined pointer provided to [SDL_SetX11EventHook](SDL_SetX11EventHook). | | **xevent** | a pointer to an Xlib XEvent union to process. | ## Return Value Returns true to let event continue on, false to drop it. ## Remarks This callback may modify the event, and should return true if the event should continue to be processed, or false to prevent further processing. As this is processing an event directly from the X11 event loop, this callback should do the minimum required work and return quickly. ## Thread Safety This may only be called (by SDL) from the thread handling the X11 event loop. ## Version This datatype is available since SDL 3.2.0. ## See Also - [SDL_SetX11EventHook](SDL_SetX11EventHook) ---- [CategoryAPI](CategoryAPI), [CategoryAPIDatatype](CategoryAPIDatatype), [CategorySystem](CategorySystem)