-class WXDLLEXPORT wxButton;
-class WXDLLEXPORT wxStaticLine;
-
-// class name
-extern WXDLLIMPEXP_DATA_CORE(const wxChar) wxCollapsiblePaneNameStr[];
+class WXDLLIMPEXP_FWD_CORE wxButton;
+class WXDLLIMPEXP_FWD_CORE wxStaticLine;
+#if defined( __WXMAC__ ) && !defined(__WXUNIVERSAL__)
+class WXDLLIMPEXP_FWD_CORE wxDisclosureTriangle;
+#endif