debian man page for mouse_on_screen

mouse_on_screen(3alleg4)					  Allegro manual					  mouse_on_screen(3alleg4)

NAME
       mouse_on_screen - Tells you whether the mouse pointer is currently on screen. Allegro game programming library.

SYNOPSIS
       #include <allegro.h>

       int mouse_on_screen();

DESCRIPTION
       This  function can be useful to prevent having two mouse pointers on the screen at the same time when running your program in windowed mode
       and drawing the mouse pointer yourself. Other possible uses include the ability to pause your game when the mouse goes off of  the  window,
       or only scrolling the view when the pointer is near the edge of the window, but not while off of the window.

       Example :

	  if (mouse_on_screen()) {draw_sprite(buffer , mouse_sprite , mouse_x , mouse_y);}

RETURN VALUE
       Returns 0 if the mouse pointer is off of the screen, or non-zero otherwise.

Allegro 							   version 4.4.2					  mouse_on_screen(3alleg4)