SDL_MessageBoxData.3type - Man Page

#include <SDL3/SDL_messagebox.h>

typedef struct SDL_MessageBoxData
{
    SDL_MessageBoxFlags flags;
    SDL_Window *window;                 /**< Parent window, can be NULL */
    const char *title;                  /**< UTF-8 title */
    const char *message;                /**< UTF-8 message text */

    int numbuttons;
    const SDL_MessageBoxButtonData *buttons;

    const SDL_MessageBoxColorScheme *colorScheme;   /**< SDL_MessageBoxColorScheme, can be NULL to use system settings */
} SDL_MessageBoxData;

This struct is available since SDL 3.2.0.