Thank you friend, I was able to achieve what I wanted. It would have been better to link it in the dynamic view from the pop-up rather than to switch views; but still at least now it is possible. :)

If you want a more dynamic use of this feature, create a module to insert a binary filed in the calendar view. It's simple to do...:)

I haven't written any of my own modules yet, I know how to inherit a view - but do you know where I could find the information on how to add this type of field to link to the attachments? Any similar topic would suffice, I can deduce it from the context.

This (http://doc.openerp.com/v6.0/developer/index.html) is a simple documentation to develop an openerp module. It's not simple if you doesn't written a module, never.