Event.observe(document, "dom:loaded", function() {
    
    init();
    
    var imgs = $$('img.right-nav-button');
    
    for (var i = 0; i < imgs.length; i++) {
      var img = imgs[i];
      var src = img.src;
      var src_len = img.src.length;
      var src_end = img.src.substring(src_len-7);
      var base_src = img.src.substring(0,src_len-7); 
      var mo_src = base_src+'_mo'+src_end;
      rightNavButtonMoEvent(img, src, mo_src);
    }
});

function rightNavButtonMoEvent (img, off, on) {

  Event.observe(img, "mouseover", function () {
      img.src=on;
  });
  
  Event.observe(img, "mouseout", function () {
      img.src=off;
  });
}