Shows custom array controller that implements table view data source methods to support drag and drop, including copying objects from one window to another, 
drop of URLs, and re-ordering of the content array.

Originally from `Cocoa Bindings Examples and Hints`__, converted to PyObjC by 
u.fiedler.

.. __: http://homepage.mac.com/mmalc/CocoaExamples/controllers.html
