In Part 1, Shell Style Drag and Drop in .NET (WPF and WinForms), I opened up the discussion about implementing a nice Shell style drag image, like that of Windows Explorer, in C#. This involved exposing a couple of COM interfaces to .NET, as well as implementing the COM IDataObject interface. In Shell Style Drag and Drop in .NET - Part 2 I took it to the next step, implementing some extension methods and a helper class. These made it easy to use the COM interfaces to achieve Shell integration.
In Part 3, I will open the door even wider. My aim is to achieve complete Shell integration. First, I will look at adding a drop description. This is the little preview text that tells you what you would do by dropping at the current location. It is a dynamic text with an icon, indicating whether you are moving, copying, linking, etc. Then I'll look at handling all the drag source plumbing in a consistent fashion through the use of a new class, the DragSourceHelper. Unlike the DropTargetHelper class from Part 2, the DragSourceHelper actually has a decent amount of work to do.