rem:  if (promptService) promptService.alert(window, errorTitle, errorMsg); 
add: if (!gPromptService) { gPromptService = Components.classes["@mozilla.org/embedcomp/prompt-service;1"].getService(); gPromptService = gPromptService.QueryInterface(Components.interfaces.nsIPromptService); } if (gPromptService) gPromptService.alert(window, errorTitle, errorMsg); 
context:   onDrop: function (aEvent, aData, aDragSession)    {      var prettyName;      var rawData = aData.data;      switch (aData.flavour.contentType) {      case "text/x-moz-url":      case "text/nsmessage":        var separator = rawData.indexOf("\n");        if (separator != -1) {          prettyName = rawData.substr(separator+1);          rawData = rawData.substr(0,separator);        }        break;      case "application/x-moz-file":    	  rawData = aData.data.URL;        break;      }      if (!(DuplicateFileCheck(rawData)))        AddAttachment(rawData, prettyName);      else {        var errorTitle = gComposeMsgsBundle.getString("DuplicateFileErrorDlogTitle");        var errorMsg = gComposeMsgsBundle.getString("DuplicateFileErrorDlogMessage");        if (promptService)          promptService.alert(window, errorTitle, errorMsg);        else          window.alert(errorMsg);      }    },
meta: 8395	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/8395/58c2cb97b722e415727774a9972e3080113344e5/MsgComposeCommands.js/buggy/mailnews/compose/resources/content/MsgComposeCommands.js