Compile fixes for GTK 2.4

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39512 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/window.cpp

@@ -2746,10 +2746,12 @@ void wxWindowGTK::PostCreation()
                           G_CALLBACK (wxgtk_combo_size_request_callback),
                           this);
     }
+#ifdef GTK_IS_FILE_CHOOSER_BUTTON
     else if (GTK_IS_FILE_CHOOSER_BUTTON(m_widget))
     {
         // FIXME: what should be done here ?
     }
+#endif
     else
     {
         // This is needed if we want to add our windows into native