var nav ;
 if (navigator.appVersion.indexOf('MSIE')!=-1) {
  	nav = 'IE'
 } else {
  	nav = 'N'
 }


	function obrirfinestra_centre (url, nom, ample, alta) {
			ampl = screen.availWidth/2;
			alt = screen.availHeight/2;
			_left=ampl-ample/2;
			_top=alt-alta/2;			
			finestra = window.open(url, nom, "toolbar=no,location=no,scrollbars=no,resizable=no,width="+ample+",height="+alta+",top=" + _top + ",left=" + _left);			
			finestra.focus(); 
	}
	
	function obrirfinestra_centre2 (url, nom, ample, alta) {
			ampl = screen.availWidth/2;
			alt = screen.availHeight/2;
			_left=ampl-ample/2;
			_top=alt-alta/2;			
			finestra = window.open(url, nom, "toolbar=no,location=no,scrollbars=si,resizable=no,width="+ample+",height="+alta+",top=" + _top + ",left=" + _left);			
			finestra.focus(); 
	}