function obret(pagina,ample,alt,scroll,finestrapagina,resize)
{
	if (scroll=="si")d=1;
	if (scroll=="no")d=0;
	if (scroll=="")d=0;
	
	LeftPosition = (screen.width) ? (screen.width-ample)/2 : 0;
	TopPosition = (screen.height) ? (screen.height-alt)/2 : 0;

	settings='width='+ample+',height='+alt+',top='+TopPosition+',left='+LeftPosition+',scrollbars='+d+',location=no,directories=no,status=no,menubar=no,toolbar=no,resizable='+resize+'';
	win=window.open(pagina,finestrapagina,settings);
	//Focus de la finestra
	win.focus();	
}