Fix Zotero menu on OS X, part 1

Create a hidden window with a menu bar, since it loads first

chrome/content/zotero-platform/mac/standalone/menuOverlay.xul

@@ -84,7 +84,7 @@
         <menuitem id="menu_preferences"
 				label="&preferencesCmdMac.label;"
 				key="key_preferencesCmdMac"
-				oncommand="ZoteroPane.openPreferences();"/>
+				oncommand="Components.classes['@mozilla.org/appshell/window-mediator;1'].getService(Components.interfaces.nsIWindowMediator).getMostRecentWindow('navigator:browser').ZoteroPane.openPreferences();"/>
         <menuitem id="menu_mac_services"
 				label="&servicesMenuMac.label;"/>
         <menuitem id="menu_mac_hide_app"

chrome/content/zotero/standalone/hiddenWindow.xul

@@ -0,0 +1,55 @@
+<?xml version="1.0"?>
+<!--
+    ***** BEGIN LICENSE BLOCK *****
+    
+    Copyright © 2009 Center for History and New Media
+                     George Mason University, Fairfax, Virginia, USA
+                     http://zotero.org
+    
+    This file is part of Zotero.
+    
+    Zotero is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+    
+    Zotero is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+    
+    You should have received a copy of the GNU Affero General Public License
+    along with Zotero.  If not, see <http://www.gnu.org/licenses/>.
+    
+    ***** END LICENSE BLOCK *****
+-->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<?xul-overlay href="chrome://zotero-platform/content/standalone/menuOverlay.xul"?>
+
+<!DOCTYPE window [
+	<!ENTITY % globalDTD SYSTEM "chrome://global/locale/global.dtd"> %globalDTD;
+	<!ENTITY % textcontextDTD SYSTEM "chrome://global/locale/textcontext.dtd" > %textcontextDTD;
+	<!ENTITY % standaloneDTD SYSTEM "chrome://zotero/locale/standalone.dtd" > %standaloneDTD;
+	<!ENTITY % brandDTD SYSTEM "chrome://branding/locale/brand.dtd" > %brandDTD;
+	<!ENTITY % zoteroDTD SYSTEM "chrome://zotero/locale/zotero.dtd"> %zoteroDTD;
+]>
+
+<window id="main-window" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+	<commandset id="mainCommandSet">
+		<!--FILE-->
+		<command id="cmd_quitApplication" oncommand="goQuitApplication();"/>
+		<command id="cmd_close" oncommand="window.close();"/>
+	</commandset>
+	
+	<keyset id="mainKeyset">
+		<key id="key_close" key="&closeCmd.key;" command="cmd_close" modifiers="accel"/>
+	</keyset>
+
+	<menubar id="main-menubar">
+		<menu id="fileMenu" label="&fileMenu.label;" accesskey="&fileMenu.accesskey;">
+			<menupopup id="menu_FilePopup"/>
+		</menu>
+	</menubar>
+</window>