rem: var string = XPCU.QI(data.value, "nsISupportsWString"); 
add: var string = XPCU.QI(data.value, "nsISupportsString"); 
context:   onDragDrop: function(aEvent)  {    this.markColumnInsert(null);    var dragService = XPCU.getService("@mozilla.org/widget/dragservice;1", "nsIDragService");    var dragSession = dragService.getCurrentSession();    if (!dragSession.isDataFlavorSupported("TreeBuilder/column-add"))      return false;    var trans = XPCU.createInstance("@mozilla.org/widget/transferable;1", "nsITransferable");    trans.addDataFlavor("TreeBuilder/column-add");    dragSession.getData(trans, 0);    var data = {};    trans.getAnyTransferData ({}, data, {});    var string = XPCU.QI(data.value, "nsISupportsWString");    this.insertColumn(this.mColumnInsertIndex,      {        name: string.data,        title: string.data,        flex: 1      });            // if we rebuildContent during this thread, it will crash in the dnd service    setTimeout(function(me) { me.build(); me.buildContent() }, 1, this);    // bug 56270 - dragSession.sourceDocument is null --    // causes me to code this very temporary, very nasty hack    // to tell columnsDialog.js about the drop    if (this.mTree.onClientDrop) {      this.mTree.onClientDrop();    }  },
meta: 8395	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/8395/f7ad4265ef6a40ea01c54009718ef28974e67fe9/inTreeBuilder.js/buggy/extensions/inspector/resources/content/jsutil/xul/inTreeBuilder.js