is_windowed_mode - Man Page

#include <allegro.h>

int is_windowed_mode(void);

This function can be used to detect whether or not set_gfx_mode() selected a windowed mode. Example:

   if (set_gfx_mode(GFX_AUTODETECT, 640, 480, 0, 0) != 0)
      abort_on_error("Couldn't set graphic mode!");
   if (is_windowed_mode()) {
      /* Windowed mode stuff. */
   } else {
      /* Fullscreen mode stuff. */
   }

Returns true if the current graphics mode is a windowed mode, or zero if it is a fullscreen mode. You should not call this function if you are not in graphics mode.

set_gfx_mode(3)

get_gfx_mode(3), get_gfx_mode_type(3).