List of classes which should use their native GTK+ equivalents but don't:

- wxStatusBar:
    Problem with multiple fields, GtkStatusbar only seems to support one pane

- wxTreeCtrl
    Ryan Norton has implemented this
    
- wxListCtrl
    Could be reimplemeted in terms of wxDataViewCtrl?

- wxSplitterWindow
    Not possible because GTK's GtkHPane and GtkVPane
    only support either horizontal or vertical panes
    (therefore their names) whereas wxSplitterWindow
    supports both and can even change orientiation at
    runtime.

- wxDatePickerCtrl
- wxCalendarCtrl
    Use GtkCalendar

- wxWizard
    Can GtkAssistant be used?
