wxSizer already has m_minSize field, use m_calculatedMinSize for the field of the derived wxBoxSizer class to avoid confusion, just as wxFlexGridSizer already did. Also add a new unit test checking that GetMinSize() still works after this change.
wxSizer already has m_minSize field, use m_calculatedMinSize for the field of the derived wxBoxSizer class to avoid confusion, just as wxFlexGridSizer already did. Also add a new unit test checking that GetMinSize() still works after this change.