Further attempts at getting the header buttons right

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@58299 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/private.h

@@ -122,6 +122,7 @@ GtkWidget *GetCheckButtonWidget();
 GtkWidget *GetComboBoxWidget();
 GtkWidget *GetEntryWidget();
 GtkWidget *GetHeaderButtonWidgetFirst();
+GtkWidget *GetHeaderButtonWidgetLast();
 GtkWidget *GetHeaderButtonWidget();
 GtkWidget *GetRadioButtonWidget();
 GtkWidget *GetSplitterWidget();