Add wxTreeListCtrl::GetView() and GetDataView().

It can be useful to have access to the window used to actually show the items
by wxTreeListCtrl, provide two accessors for m_view: a wxDataViewCtrl-specific
one and a generic one returning just a wxWindow that can be used to keep the
code isolated from wxDataViewCtrl.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@69173 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/treelist.cpp

@@ -1548,6 +1548,15 @@ void wxTreeListCtrl::OnSize(wxSizeEvent& event)
     }
 }
 
+wxWindow* wxTreeListCtrl::GetView() const
+{
+#ifdef wxHAS_GENERIC_DATAVIEWCTRL
+    return m_view->GetMainWindow();
+#else
+    return m_view;
+#endif
+}
+
 // ============================================================================
 // wxTreeListEvent implementation
 // ============================================================================