在VS的IDE的Debug中写一行

				try
				{
					// Argument excepion handle when the target
					// itemssource can not accept the data
					// draggedTreeItem - e.g. different types
					collection.Insert(targetIndex, draggedItem);
				}
				catch (InvalidCastException exc)
				{
					System.Diagnostics.Debug.WriteLine(exc.Message);
				}
				catch (ArgumentException exc)
				{
					System.Diagnostics.Debug.WriteLine(exc.Message);
				}