automated changes: many (pure) virtual specifiers added

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@56276 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/htmllbox.h

@@ -125,7 +125,7 @@ protected:
         that the returned HTML fragment will render with the same height or else you'll
         see some artifacts when the user selects an item.
     */
-    wxString OnGetItem(size_t n) const;
+    virtual wxString OnGetItem(size_t n) const = 0;
 };