<?xml version="1.0"?>
<overlay id="stayopenmenu"
  xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" >
    <menu id="bookmarksMenuPopup" onclick='if(event.button != 1) {return;}
      BookmarksEventHandler.onCommand(event)' />
    <hbox id="bookmarksBarContent" onclick='if(event.button != 1) {return;}
      BookmarksEventHandler.onCommand(event);' />
    <menu id="history-menu" onclick="if(event.button != 1) {return;}
      var node = event.target.node; if (node) { PlacesUIUtils.markPageAsTyped(node.uri); openUILink(node.uri, event, false, true);}" />
</overlay>

//隱藏選單列
document.getElementById("toolbar-menubar").collapsed = true;
//再來一次, 雙重保險
document.getElementById("toolbar-menubar").setAttribute("collapsed", true);
//測試以上兩行是否能運作, 沒問題的話就會彈出對話視窗
alert("");