The best practise is still to specify the exact field to be visualised.
However, the default for "field" is now None, not 'BtEn', so there's a small possibility of a breaking change for those relying on this, who also specified a numerical radius. As now field = None causes a search based on field_prefix = 'Bt', the search could pick up BtE500 before BtEn for example.
This is an edge case to let a new convenience helper work, not a major API change, so I have only bumped a minor version number.