function nuevaventana(thePage,name,wt,ht,sc,res){ 
	leftPos= (screen.width-wt)/6 
	topPos = (screen.height-ht)/6 
	eval("win_"+name+" = window.open(thePage,name,'toolbars=yes, resizable='+res+',scrollbars="+sc+",left="+leftPos+",top="+topPos+",width="+wt+",height="+ht+"')");
}