three_finger_flag - Man Page

#include <allegro.h>

extern int three_finger_flag;

The DJGPP keyboard handler provides an 'emergency exit' sequence which you can use to kill off your program. If you are running under DOS this  is the three finger salute, ctrl+alt+del. Most multitasking OS's will  trap this combination before it reaches the Allegro handler, in which  case you can use the alternative ctrl+alt+end. If you want to disable  this behaviour in release versions of your program, set this flag to  FALSE.

install_keyboard(3)

install_keyboard(3).