Fix comparing items with checkboxes in wxTreeListCtrl and make it simpler to correctly implement item comparison in other wxDataViewCtrl-derived classes. See https://github.com/wxWidgets/wxWidgets/pull/558
Fix comparing items with checkboxes in wxTreeListCtrl and make it simpler to correctly implement item comparison in other wxDataViewCtrl-derived classes. See https://github.com/wxWidgets/wxWidgets/pull/558