how do I open shadowbox directly in js with handleOversize=drag as a parameter?

Hi,
I'm trying to get to work the function shadowbox.open with handleOversize=drag as parameters, among others, but I don't get it properly, it just take the default value (resize)
The parameters passed to the function shadowbox.open work without any trouble, but this handleOversize don't
¿Can anyone help?

here is the code:

Shadowbox.loadSkin('classic', '../../../../plantilla/zigurat_base/src/skin');
      Shadowbox.loadLanguage('es', '../../../../plantilla/zigurat_base/src/lang');
      Shadowbox.loadPlayer(['html', 'iframe', 'flv', 'img', 'qt', 'swf', 'wmp'], '../../../../plantilla/zigurat_base/src/player');

      
      window.onload = function(){

            Shadowbox.init();      
      };


var openShadowbox = function(content, player, title){
      Shadowbox.open({            
            content:                  content,
            player:                        player,
            title:                        title,
            handleOversize:            'drag'
      });
};


para abrir la shadowbox:
<a href="javascript:openShadowbox('recursos/inicio.jpg','img','Control estad&iacute;stico del hormig&oacute;n');">Ver ejemplo</a>



Thank you for your time