Hi list, thanks a lot for has written ghemical!..it's a wonderful software! We want to introduce a new selection mode, with which you can select secondary structure, as alpha-helix or beta-sheets. Do you think should be quite easy or not? Could you point us to the right piece of code that manages the contextual menu and in particular the selection mode? Is there a manual to hack on ghemical? Claudio Forcato Michele Mattioni