Creating custom properties

["Paul Watson" <pwatson redlinepy com>]

I would like to be able to create custom properties on a shape to store additional metadata.  Is this possible?  Is this only possible if I create the shapes?

Can a shape have code executed when an event, such as selecting, it occurs?  Can this be written in Python?

I used Google and could not find anything.  The Dia--list search page says that searching crashed sometime last year.  Thanks for you help.