function show_legend(key,lang){
  var url = "button_legend.php?key=" + key + "&lang=" + lang;
  legend_w=window.open(url,"legend","width=500,height=360,screenX=0,screenY=0,left=0,top=0,resizable=yes");
  legend_w.moveTo(0,0);
  legend_w.focus();
}