Allow drag'n'drop reordering of assembly tree nodes.

ILSpy/AssemblyListTreeNode.cs

@@ -7,6 +7,8 @@ using System.IO;
 using System.Linq;
 using System.Text;
 using System.Threading;
+using System.Windows;
+
 using ICSharpCode.TreeView;
 using Mono.Cecil;
 
@@ -33,9 +35,33 @@ namespace ICSharpCode.ILSpy
 				this.Children.Remove(node);
 		}
 		
-		public override DropEffect CanDrop(System.Windows.IDataObject data, DropEffect requestedEffect)
+		public override DropEffect CanDrop(IDataObject data, DropEffect requestedEffect)
+		{
+			if (data.GetDataPresent(AssemblyTreeNode.DataFormat))
+				return DropEffect.Move;
+			else
+				return DropEffect.None;
+		}
+		
+		public override void Drop(IDataObject data, int index, DropEffect finalEffect)
 		{
-			return requestedEffect;
+			string[] files = data.GetData(AssemblyTreeNode.DataFormat) as string[];
+			if (files != null) {
+				var nodes = (from file in files
+				             select OpenAssembly(file) into node
+				             where node != null
+				             select node).Distinct().ToList();
+				foreach (AssemblyTreeNode node in nodes) {
+					int nodeIndex = this.Children.IndexOf(node);
+					if (nodeIndex < index)
+						index--;
+					this.Children.RemoveAt(nodeIndex);
+				}
+				nodes.Reverse();
+				foreach (AssemblyTreeNode node in nodes) {
+					this.Children.Insert(index, node);
+				}
+			}
 		}
 		
 		public AssemblyTreeNode OpenAssembly(string file)

ILSpy/AssemblyTreeNode.cs

@@ -152,10 +152,12 @@ namespace ICSharpCode.ILSpy
 			Parent.DeleteCore(nodes); // handle deletion in the AssemblyListTreeNode
 		}
 		
+		internal const string DataFormat = "ILSpyAssemblies";
+		
 		public override IDataObject Copy(SharpTreeNode[] nodes)
 		{
 			DataObject dataObject = new DataObject();
-			dataObject.SetData("ILSpyAssemblies", nodes.OfType<AssemblyTreeNode>());
+			dataObject.SetData(DataFormat, nodes.OfType<AssemblyTreeNode>().Select(n => n.fileName).ToArray());
 			return dataObject;
 		}
 	}

SharpTreeView/SharpTreeNode.cs

@@ -558,6 +558,7 @@ namespace ICSharpCode.TreeView
 
 		public virtual void Drop(IDataObject data, int index, DropEffect finalEffect)
 		{
+			throw new NotSupportedException(GetType().Name + " does not support Drop()");
 		}
 
 		#endregion

SharpTreeView/SharpTreeView.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Text;
 using System.Windows.Controls;
@@ -251,12 +252,17 @@ namespace ICSharpCode.TreeView
 
 		internal void HandleDrop(SharpTreeViewItem item, DragEventArgs e)
 		{
-			HidePreview();
-			e.Handled = true;
+			try {
+				HidePreview();
+				e.Handled = true;
 
-			var target = GetDropTarget(item, e);
-			if (target != null) {
-				target.Node.InternalDrop(e, target.Index);
+				var target = GetDropTarget(item, e);
+				if (target != null) {
+					target.Node.InternalDrop(e, target.Index);
+				}
+			} catch (Exception ex) {
+				Debug.WriteLine(ex.ToString());
+				throw;
 			}
 		}