var ns_pos = (typeof window.pageYOffset!='undefined');
var khtml = ((navigator.userAgent).indexOf("KHTML") >= 0 ? true : false);
var opera = ((navigator.userAgent).indexOf("Opera") >= 0 ? true : false);
var ie7 = (!ns_pos && navigator.userAgent.indexOf("MSIE 7") != -1);

window.onload = startup; // equivalent to onload on body element
function startup() { document.onkeydown = keyDown; }

function cancel(event) {
  if (event) {
     event.cancel = true;
     event.returnValue = false;

    if (event.preventDefault)
      event.preventDefault();
  }
  return false;
}

function keyDown(event) {
    var key;

    if (!event)
      var event = window.event;

    // kludge around NS/IE differences 
    if (window.event)
       key = window.event.keyCode;
    else if (event.which)
       key = event.which;
    else
       return true; // Yikes! unknown browser

    // ignore event if key value is zero
    // as for alt on Opera and Konqueror
    if (!key)
       return true;

    if (event.ctrlKey || event.altKey || event.metaKey) return true;
	   
    if (key == 32) // space bar
    {
       nextImage();
       return cancel(event);
    }
    else if (key == 38) // Arrow Up
    {
       thumbnails();
       return cancel(event);
    }
	else if (key == 37) // Left arrow
    {
       previousImage();
       return cancel(event);
    }
    if (key == 34) // Page Down
    {
       nextImage();
       return cancel(event);
    }
    else if (key == 33) // Page Up
    {
       previousImage();
       return cancel(event);
    }
    else if (key == 39) // Right arrow
    {
       nextImage();
       return cancel(event);
    }
   else if (key == 36) // Home
    {
       firstImage();
       return cancel(event);
    }
    else if (key == 35) // End
    {
       lastImage();
       return cancel(event);
    }
	return true;
}