is_game_window_active
This function checks whether your game window is currently in focus.
bool is_game_window_active()
Parameters:
None.
Return value:
true if your game window is currently active, false otherwise.
Remarks:
This function returns true if your game window has keyboard focus at the present time. It is imperative that you call show_game_window before you rely on this function.
Example:

    // Play a looping sound only while the game window has focus.

    void main()
    {
    show_game_window("Temperamental Sound");
    sound noise;
    noise.load("myfile.ogg");
    if(noise.active==false)
    {
    alert("Error", "The sound could not be loaded.");
    exit();
    }
    while(true)
    {
    if((key_down(KEY_LMENU))&&(key_pressed(KEY_F4)))
    {
    exit();
    }
    if(is_game_window_active()==true)
    {
    if(noise.playing==false)
    {
    noise.play_looped();
    }
    }
    else
    {
    if(noise.playing==true)
    {
    noise.pause();
    }
    }
    wait(5);
    }
    }