I also ran into this issue when working with a third party component that also set e.Handlet = true. Was able to override that behavior by extending the class that did this. However, it seems to me that the logic of Map is flawed. Where it should override OnMouseLeftButtonDown, it subscribes to the event. In that case, it doesn't follow the natural flow of overriding this event. A suggested fix for this issue would be to pass in the e.Handled when dispatching the delegate for performing the logic.
There are probably reasons why the design is as it is, but is this something that will be fixed? I am yet on version 2.x of the control, so I have not been able to verify if it has been resolved in 10.1.