Fix moving projects between solution folders.

src/AddIns/Debugger/Debugger.Core/TypeSystemExtensions.cs

@@ -237,7 +237,7 @@ namespace Debugger
 							0, elementType);
 					}
 				default:
-					throw new System.Exception("Invalid value for TypeKind");
+					throw new System.Exception("Invalid value for TypeKind: " + type.Kind);
 			}
 		}
 		

src/Main/Base/Project/Dom/SimpleModelCollection.cs

@@ -122,13 +122,39 @@ namespace ICSharpCode.SharpDevelop.Dom
 		
 		#region IMutableModelCollection implementation
 		
+		/// <summary>
+		/// Called immediately when an item is removed; even within a batch.
+		/// The collection may be in an invalid state while this method is called.
+		/// </summary>
+		protected virtual void OnRemove(T item)
+		{
+			if (addedItems != null && addedItems.Remove(item))
+				return;
+			if (removedItems == null)
+				removedItems = new List<T>();
+			removedItems.Add(item);
+		}
+		
+		/// <summary>
+		/// Called immediately when an item is added; even within a batch.
+		/// The collection may be in an invalid state while this method is called.
+		/// </summary>
+		protected virtual void OnAdd(T item)
+		{
+			if (removedItems != null && removedItems.Remove(item))
+				return;
+			if (addedItems == null)
+				addedItems = new List<T>();
+			addedItems.Add(item);
+		}
+		
 		public void Clear()
 		{
 			CheckReentrancy();
 			addedItems = null;
-			if (removedItems == null)
-				removedItems = new List<T>();
-			removedItems.AddRange(list);
+			for (int i = 0; i < list.Count; i++) {
+				OnRemove(list[i]);
+			}
 			list.Clear();
 			RaiseEventIfNotInBatch();
 		}
@@ -137,11 +163,7 @@ namespace ICSharpCode.SharpDevelop.Dom
 		{
 			CheckReentrancy();
 			ValidateItem(item);
-			if (removedItems != null)
-				removedItems.Remove(item);
-			if (addedItems == null)
-				addedItems = new List<T>();
-			addedItems.Add(item);
+			OnAdd(item);
 			list.Add(item);
 			RaiseEventIfNotInBatch();
 		}
@@ -155,15 +177,9 @@ namespace ICSharpCode.SharpDevelop.Dom
 			for (int i = 0; i < itemsList.Count; i++) {
 				ValidateItem(itemsList[i]);
 			}
-			if (removedItems != null) {
-				for (int i = 0; i < itemsList.Count; i++) {
-					removedItems.Remove(itemsList[i]);
-				}
+			for (int i = 0; i < itemsList.Count; i++) {
+				OnAdd(itemsList[i]);
 			}
-			if (addedItems != null)
-				addedItems.AddRange(itemsList);
-			else
-				addedItems = itemsList;
 			list.AddRange(itemsList);
 			RaiseEventIfNotInBatch();
 		}
@@ -172,11 +188,7 @@ namespace ICSharpCode.SharpDevelop.Dom
 		{
 			CheckReentrancy();
 			if (list.Remove(item)) {
-				if (addedItems != null)
-					addedItems.Remove(item);
-				if (removedItems == null)
-					removedItems = new List<T>();
-				removedItems.Add(item);
+				OnRemove(item);
 				RaiseEventIfNotInBatch();
 				return true;
 			} else {
@@ -190,11 +202,7 @@ namespace ICSharpCode.SharpDevelop.Dom
 			int count = list.RemoveAll(
 				delegate(T obj) {
 					if (predicate(obj)) {
-						if (addedItems != null)
-							addedItems.Remove(obj);
-						if (removedItems == null)
-							removedItems = new List<T>();
-						removedItems.Add(obj);
+						OnRemove(obj);
 						return true;
 					} else {
 						return false;

src/Main/Base/Project/Src/Gui/Components/ExtTreeView/ExtTreeView.cs

@@ -416,10 +416,15 @@ namespace ICSharpCode.SharpDevelop.Gui
 				// OnDragDrop raises without OnDragOver for the node.
 				// So we have to call HandleDragOver to ensure that we don't call DoDragDrop for
 				// invalid operations.
-				HandleDragOver(e, node);
-				if (e.Effect != DragDropEffects.None) {
-					node.DoDragDrop(e.Data, e.Effect);
-					SortParentNodes(node);
+				try {
+					HandleDragOver(e, node);
+					if (e.Effect != DragDropEffects.None) {
+						node.DoDragDrop(e.Data, e.Effect);
+						SortParentNodes(node);
+					}
+				} catch (Exception ex) {
+					// WinForms silently discards exceptions in the drag'n'drop events; so we need to catch+report any errors
+					SD.MessageService.ShowException(ex);
 				}
 			}
 		}

src/Main/Base/Project/Src/Gui/Pads/ProjectBrowser/TreeNodes/SolutionFolderNode.cs

@@ -169,14 +169,7 @@ namespace ICSharpCode.SharpDevelop.Project
 				Guid guid = Guid.Parse(dataObject.GetData(typeof(ISolutionItem).ToString()).ToString());
 				ISolutionItem solutionItem = folderNode.Solution.GetItemByGuid(guid);
 				if (solutionItem != null) {
-					// Use a batch update to move the item without causing projects
-					// be removed from the solution (and thus disposed).
-					using (solutionItem.ParentFolder.Items.BatchUpdate()) {
-						using (folderNode.Folder.Items.BatchUpdate()) {
-							solutionItem.ParentFolder.Items.Remove(solutionItem);
-							folderNode.Folder.Items.Add(solutionItem);
-						}
-					}
+					MoveItem(solutionItem, folderNode.Folder);
 					ExtTreeView treeView = (ExtTreeView)folderTreeNode.TreeView;
 					foreach (ExtTreeNode node in treeView.CutNodes) {
 						ExtTreeNode oldParent = node.Parent as ExtTreeNode;
@@ -192,7 +185,19 @@ namespace ICSharpCode.SharpDevelop.Project
 			}
 			folderTreeNode.Expand();
 		}
-		
+
+		internal static void MoveItem(ISolutionItem solutionItem, ISolutionFolder folder)
+		{
+			// Use a batch update to move the item without causing projects
+			// be removed from the solution (and thus disposed).
+			using (solutionItem.ParentFolder.Items.BatchUpdate()) {
+				using (folder.Items.BatchUpdate()) {
+					solutionItem.ParentFolder.Items.Remove(solutionItem);
+					folder.Items.Add(solutionItem);
+				}
+			}
+		}
+
 		public override bool EnablePaste {
 			get {
 				return DoEnablePaste(this);
@@ -255,7 +260,8 @@ namespace ICSharpCode.SharpDevelop.Project
 				folderNode.Remove();
 				folderNode.InsertSorted(this);
 				folderNode.EnsureVisible();
-				this.folder.Items.Add(folderNode.Folder);
+				MoveItem(folderNode.Folder, this.folder);
+				
 				if (parentNode != null) {
 					parentNode.Refresh();
 				}
@@ -264,9 +270,7 @@ namespace ICSharpCode.SharpDevelop.Project
 			if (dataObject.GetDataPresent(typeof(SolutionItemNode))) {
 				SolutionItemNode solutionItemNode = (SolutionItemNode)dataObject.GetData(typeof(SolutionItemNode));
 				
-				ISolutionFolderNode folderNode = (ISolutionFolderNode)solutionItemNode.Parent;
-				folderNode.Folder.Items.Remove(solutionItemNode.SolutionItem);
-				Folder.Items.Add(solutionItemNode.SolutionItem);
+				MoveItem(solutionItemNode.SolutionItem, this.folder);
 				
 				solutionItemNode.Remove();
 				solutionItemNode.InsertSorted(this);
@@ -282,7 +286,7 @@ namespace ICSharpCode.SharpDevelop.Project
 				projectNode.Remove();
 				projectNode.InsertSorted(this);
 				projectNode.EnsureVisible();
-				this.folder.Items.Add(projectNode.Project);
+				MoveItem(projectNode.Project, this.folder);
 				
 				if (projectNode.Parent != null) {
 					((ExtTreeNode)projectNode.Parent).Refresh();

src/Main/Base/Project/Src/Gui/Pads/ProjectBrowser/TreeNodes/SolutionNode.cs

@@ -119,7 +119,7 @@ namespace ICSharpCode.SharpDevelop.Project
 				folderNode.Remove();
 				folderNode.InsertSorted(this);
 				
-				this.solution.Items.Add(folderNode.Folder);
+				SolutionFolderNode.MoveItem(folderNode.Folder, this.solution);
 			}
 			if (dataObject.GetDataPresent(typeof(ProjectNode))) {
 				ProjectNode projectNode = (ProjectNode)dataObject.GetData(typeof(ProjectNode));
@@ -128,7 +128,7 @@ namespace ICSharpCode.SharpDevelop.Project
 				projectNode.Remove();
 				projectNode.InsertSorted(this);
 				projectNode.EnsureVisible();
-				this.solution.Items.Add(projectNode.Project);
+				SolutionFolderNode.MoveItem(projectNode.Project, this.solution);
 			}
 			
 			if (parentNode != null) {

src/Main/SharpDevelop/Project/SolutionFolder.cs

@@ -68,15 +68,25 @@ namespace ICSharpCode.SharpDevelop.Project
 				return new CompositeDisposable(base.BatchUpdate(), folder.parentSolution.ReportBatch());
 			}
 			
+			protected override void OnAdd(ISolutionItem item)
+			{
+				base.OnAdd(item);
+				item.ParentFolder = folder;
+			}
+			
+			protected override void OnRemove(ISolutionItem item)
+			{
+				base.OnRemove(item);
+				item.ParentFolder = null;
+			}
+			
 			protected override void OnCollectionChanged(IReadOnlyCollection<ISolutionItem> removedItems, IReadOnlyCollection<ISolutionItem> addedItems)
 			{
 				using (folder.parentSolution.ReportBatch()) {
 					foreach (ISolutionItem item in removedItems) {
 						folder.parentSolution.ReportRemovedItem(item);
-						item.ParentFolder = null;
 					}
 					foreach (ISolutionItem item in addedItems) {
-						item.ParentFolder = folder;
 						folder.parentSolution.ReportAddedItem(item);
 					}
 				}