[NTG-context] tooltips and glossary

Does Context have a mechanism for placing tooltips on text? I think the usual PDF way is to put an invisible button over the test and set its "short description". Does anyone know how to do this? Also, is there no Context method to produce a glossary? It might be enough to produce a secondary .bib file with special entries and to print this out as a secondary "References" section, but I don't know how to do this or how to control the appearance of the printed "references".