SDL_WM_IconifyWindow man page
SDL_WM_IconifyWindow — Iconify/Minimise the window
If the application is running in a window managed environment SDL attempts to iconify/minimise it. If SDL_WM_IconifyWindow is successful, the application will receive a SDL_APPACTIVE loss event.
Returns non-zero on success or 0 if iconification is not support or was refused by the window manager.