Returns the dragging operation mask of the dragging source.
Original signature is '- (NSDragOperation)draggingSourceOperationMask'
Available in Mac OS X v10.0 and later.

C# | Visual Basic | Visual C++ |
NSDragOperation DraggingSourceOperationMask { get; }
ReadOnly Property DraggingSourceOperationMask As NSDragOperation Get
property NSDragOperation DraggingSourceOperationMask { NSDragOperation get (); }

- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)