#include "SDL.h"
void SDL_UpdateRect
(SDL_Surface *screen, Sint32 x, Sint32 y, Sint32 w, Sint32 h);
Makes sure the given area is updated on the given screen.
If 'x', 'y', 'w' and 'h' are all 0, SDL_UpdateRect will update the entire screen.
This function should not be called while 'screen' is locked.