add: item.setAttribute("type", "checkbox"); 
context:   addDictionaryListToMenu: function(menu, insertBefore)  {    this.mDictionaryMenu = menu;    this.mDictionaryNames = [];    this.mDictionaryItems = [];    if (! this.mInlineSpellChecker || ! this.enabled)      return 0;    var spellchecker = this.mInlineSpellChecker.spellChecker;    var o1 = {}, o2 = {};    spellchecker.GetDictionaryList(o1, o2);    var list = o1.value;    var listcount = o2.value;    var curlang = spellchecker.GetCurrentDictionary();    for (var i = 0; i < list.length; i ++) {      this.mDictionaryNames.push(list[i]);      var item = document.createElement("menuitem");      item.setAttribute("label", list[i]);      this.mDictionaryItems.push(item);      if (curlang == list[i]) {        item.setAttribute("checked", "true");      } else {        var callback = function(me, val) { return function(evt) { me.selectDictionary(val); } };        item.addEventListener("command", callback(this, i), true);      }      if (insertBefore)        menu.insertBefore(item, insertBefore);      else        menu.appendChild(item);    }    return list.length;  },
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/2d04e8350a0410dbe3dc34be1d3f030b71f7417d/inlineSpellCheckUI.js/clean/toolkit/content/inlineSpellCheckUI.js