Is there a way to modify existing UI element such as ZmMailMsg, ZmAppointment? For example, to add a button "call" in the ZmAppointment UI panel for Click to call a conference or in ZmMailMsg Panel to Click to Call a mail sender?

Unlike ZmContact, the content in the "Location" or any field of ZmAppointment object seems not recognized as content object if I put a phone number (for example a conference number) in the location, I am wondering it would be great if the content Object matching field could include those fields.