[Koha] How to flag a warning if item of certain Koha item type is returned?

Dear all, does anyone know about a way to flag a warning to the staff when returning an item of a defined Koha item type in the circulation module? Many thanks in advance for your answer(s), and kind regards Uwe __________________________________________________________________ (Mr.) Uwe Boettcher Director Library WHU - Otto Beisheim School of Management Campus Vallendar, Burgplatz 2, 56179 Vallendar, Germany Tel.: +49 261 6509-555 ; Fax: +49 261 6509-559 bib@whu.edu<mailto:bib@whu.edu> ; www.whu.edu<http://www.whu.edu/> ___________________________________________________________________