SDL_MessageBoxButtonFlags.3type - Man Page

SDL_MessageBoxButtonFlags — SDL_MessageBoxButtonData
flags.

Defined in SDL3/SDL_messagebox.h

#include "SDL3/SDL.h"

typedef Uint32 SDL_MessageBoxButtonFlags;

#define SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT 0x00000001u /**< Marks the default button when return is hit */
#define SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT 0x00000002u /**< Marks the default button when escape is hit */

This datatype is available since SDL 3.2.0.