in lightbox.js (se parliamo di lightbox 2.0)
Codice PHP:
    //
    //    keyboardAction()
    //
    
keyboardAction: function(e) {
        if (
== null) { // ie
            
keycode event.keyCode;
            
escapeKey 27;
        } else { 
// mozilla
            
keycode e.keyCode;
            
escapeKey e.DOM_VK_ESCAPE;
        }

        
key String.fromCharCode(keycode).toLowerCase();

        if((
key == 'x') || (key == 'o') || (key == 'c') || (keycode == escapeKey)){    // close lightbox
            
myLightbox.end();
        } else if((
key == 'p') || (keycode == 37)){    // display previous image
            
if(activeImage != 0){
                
myLightbox.disableKeyboardNav();
                
myLightbox.changeImage(activeImage 1);
            }
        } else if((
key == 'n') || (keycode == 39)){    // display next image
            
if(activeImage != (imageArray.length 1)){
                
myLightbox.disableKeyboardNav();
                
myLightbox.changeImage(activeImage 1);
            }
        }

    },