// Some variables to autodetect browser type
var ns=(document.layers);
var ie=(document.all);
var w3=(document.getElementById && !ie);

// Return an object
function get_object(id)
{ 
 if(!ns && !ie && !w3) 
   return null;
 if (ie)
   e=eval("document.all." + id);
 else if (ns)
   e=eval('document.links[id]');
 else if (w3)
   e=eval('document.getElementById(id)');
 return e;
}
// Change the current page to the id found in the page
function jumpto(id)
{
  e = get_object(id);
  if ((e != null) && (e.href != null)) {
      location.href = e.href;
  }
}

// Change the current page
function next_page()
{
  jumpto('next_slide');
}

function previous_page()
{
  jumpto('previous_slide');
}

// Event Handler that receive Key Event
function getkey(e)
{
  if (e == null)
   { // IE
     kcode = window.event.keyCode;
   } 
  else
   { // Mozilla
     kcode = e.which;
   }
  key = String.fromCharCode(kcode).toLowerCase();
  switch(key)
   {
     case "n":
     case " ":
       next_page();
       return false;
     case "p":
       previous_page();
       return false;
   }
  switch(kcode)
   {
     case 8:
       previous_page();
       return false;
   }
  return true;
}

if(w3 || ie)
{
  document.onkeypress = getkey;
} 
else
{
  document.captureEvents(Event.KEYUP);
  document.onkeyup = getkey;
  document.captureEvents(Event.KEYPRESS);
  document.onkeypress = getkey;
}