Currently, the DragDropBehavior<TState> class derives from DependencyObject which prevents it from inheritting the data context of its parent element. Change its parent class from DependencyObject to Freezable, so the data context can be automatically accessed. This is meaningful when you create a custom behavior and add a DependencyProperty that you want to data bind in the XAML. 

Enable Drag Drop using right mouse button

It would be great to be able to change the drag visual while dragging over certain controls, but when you don't have access to the DragInitialize event.

A sample scenario would be selecting a bunch of files from explorer, dragging over a grid, and the visual providing some information (such as file count, or some feedback as to what will happen on drop).