Bug #230392 --> minor thunderbird specific fix.

Create new window (if none exists) when clicking the thunderbird dock icon on Mac OS X
instead of trying to create an instance of navigator.xul.

xpfe/appshell/src/nsAppShellService.cpp

@@ -1094,7 +1094,7 @@ nsAppShellService::CreateStartupState(PRInt32 aWindowWidth, PRInt32 aWindowHeigh
 {
   NS_ENSURE_ARG_POINTER(_retval);
   nsresult rv;
-  
+#ifndef MOZ_THUNDERBIRD  
   nsCOMPtr<nsIPrefService> prefService(do_GetService(NS_PREFSERVICE_CONTRACTID));
   if (!prefService)
     return NS_ERROR_FAILURE;
@@ -1121,6 +1121,12 @@ nsAppShellService::CreateStartupState(PRInt32 aWindowWidth, PRInt32 aWindowHeigh
   }
   
   NS_FREE_XPCOM_ALLOCATED_POINTER_ARRAY(childCount, childArray);
+#else
+  PRBool windowOpened;
+  rv = LaunchTask("mail", aWindowHeight, aWindowWidth, &windowOpened);
+  if (NS_SUCCEEDED(rv) && windowOpened)
+    *_retval = PR_TRUE;
+#endif
   
   return NS_OK;
 }