Add support for the eventual inclusion of the single instance code.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@10459 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/os2/app.h

@@ -117,6 +117,7 @@ public:
     static void  CleanUp(void);
 
     static bool  RegisterWindowClasses(HAB vHab);
+    virtual void DoMessage(WXMSG *pMsg);
     virtual bool DoMessage(void);
     virtual bool ProcessMessage(WXMSG* pMsg);
     void         DeletePendingObjects(void);