gui_set_screen - Changes the bitmap surface GUI routines draw to. Allegro game programming library.

       This  function  can  be used to change the bitmap surface the GUI routines draw to. This can be useful if
       you are using a double buffering or page flipping system. Passing NULL will  cause  the  default  surface
       (screen) to be used again. Example:

          BITMAP *page[2];

          /* Allocate two pages of video memory */
          page[0] = create_video_bitmap(SCREEN_W, SCREEN_H);
          page[1] = create_video_bitmap(SCREEN_W, SCREEN_H);

          /* Page flip */
          show_video_bitmap(page[0]);
          gui_set_screen(page[0]);

       gui_set_screen - Changes the bitmap surface GUI routines draw to. Allegro game programming library.

gui_get_screen(3alleg4)

Allegro                                           version 4.4.3                          gui_set_screen(3alleg4)

#include<allegro.h>voidgui_set_screen(BITMAP*bmp);