Better comments.

src/AddIns/Debugger/Debugger.AddIn/TreeModel/ChildNodesOfObject.cs

@@ -98,7 +98,9 @@ namespace Debugger.AddIn.TreeModel
 		
 		public static IEnumerable<TreeNode> LazyGetItemsOfIList(Expression targetObject)
 		{
-			// This is needed for expanding IEnumerable<T>
+			// Add a cast, so that we are sure the expression has an indexer.
+			// (The expression can be e.g. of type 'object' but its value is a List.
+			// Without the cast, evaluating "expr[i]" would fail, because object does not have an indexer).
 			targetObject = new CastExpression(
 				new TypeReference(typeof(IList).FullName),
 				targetObject,
@@ -120,9 +122,9 @@ namespace Debugger.AddIn.TreeModel
 				for(int i = 0; i < count; i++) {
 					string imageName;
 					var image = ExpressionNode.GetImageForArrayIndexer(out imageName);
-					var expression = new ExpressionNode(image, "[" + i + "]", targetObject.AppendIndexer(i));
-					expression.ImageName = imageName;
-					yield return expression;
+					var itemNode = new ExpressionNode(image, "[" + i + "]", targetObject.AppendIndexer(i));
+					itemNode.ImageName = imageName;
+					yield return itemNode;
 				}
 			}
 		}

src/AddIns/Debugger/Debugger.AddIn/Visualizers/GridVisualizer/GridVisualizerWindow.xaml.cs

@@ -105,54 +105,61 @@ namespace Debugger.AddIn.Visualizers.GridVisualizer
 		
 		public void Refresh()
 		{
-			// clear ListView
-			listView.ItemsSource = null;
-			ScrollViewer listViewScroller = listView.GetScrollViewer();
-			if (listViewScroller != null) {
-				listViewScroller.ScrollToVerticalOffset(0);
-			}
-			Value shownValue = null;
-			ICSharpCode.NRefactory.Ast.Expression shownExpr = null;
-			try	{
-				shownExpr = debuggerService.GetExpression(txtExpression.Text);
-				shownValue = shownExpr.Evaluate(debuggerService.DebuggedProcess);
-			} catch(GetValueException) {
-				// display ex.Message
-			}
-			if (shownValue != null && !shownValue.IsNull) {
-				GridValuesProvider gridValuesProvider;
-				// Value is IList
-				DebugType iListType, listItemType;
-				if (shownValue.Type.ResolveIListImplementation(out iListType, out listItemType)) {
-					gridValuesProvider = CreateListValuesProvider(shownExpr, iListType, listItemType);
-				} else	{
-					// Value is IEnumerable
-					DebugType iEnumerableType, itemType;
-					if (shownValue.Type.ResolveIEnumerableImplementation(out iEnumerableType, out itemType)) {
-						// original
-						/*var lazyListViewWrapper = new LazyItemsControl<ObjectValue>(this.listView, initialIEnumerableItemsCount);
+			try {
+				// clear ListView
+				listView.ItemsSource = null;
+				ScrollViewer listViewScroller = listView.GetScrollViewer();
+				if (listViewScroller != null) {
+					listViewScroller.ScrollToVerticalOffset(0);
+				}
+				Value shownValue = null;
+				ICSharpCode.NRefactory.Ast.Expression shownExpr = null;
+				try	{
+					shownExpr = debuggerService.GetExpression(txtExpression.Text);
+					shownValue = shownExpr.Evaluate(debuggerService.DebuggedProcess);
+				} catch(GetValueException) {
+					// display ex.Message
+				}
+				if (shownValue != null && !shownValue.IsNull) {
+					GridValuesProvider gridValuesProvider;
+					// Value is IList
+					DebugType iListType, listItemType;
+					if (shownValue.Type.ResolveIListImplementation(out iListType, out listItemType)) {
+						gridValuesProvider = CreateListValuesProvider(shownValue, iListType, listItemType);
+					} else	{
+						// Value is IEnumerable
+						DebugType iEnumerableType, itemType;
+						if (shownValue.Type.ResolveIEnumerableImplementation(out iEnumerableType, out itemType)) {
+							// original
+							/*var lazyListViewWrapper = new LazyItemsControl<ObjectValue>(this.listView, initialIEnumerableItemsCount);
 						var enumerableValuesProvider = new EnumerableValuesProvider(val.ExpressionTree, iEnumerableType, itemType);
 						lazyListViewWrapper.ItemsSource = new VirtualizingIEnumerable<ObjectValue>(enumerableValuesProvider.ItemsSource);
 						gridValuesProvider = enumerableValuesProvider;*/
-						DebugType debugListType;
-						var debugListExpression = DebuggerHelpers.CreateDebugListExpression(shownExpr, itemType, out debugListType);
-						gridValuesProvider = CreateListValuesProvider(debugListExpression, debugListType, itemType);
-					} else	{
-						// Value cannot be displayed in GridVisualizer
-						return;
+							DebugType debugListType;
+							var debugListExpression = DebuggerHelpers.CreateDebugListExpression(shownExpr, itemType, out debugListType);
+							var debugList = debugListExpression.Evaluate(WindowsDebugger.CurrentProcess);
+							gridValuesProvider = CreateListValuesProvider(debugList, debugListType, itemType);
+						} else	{
+							// Value cannot be displayed in GridVisualizer
+							return;
+						}
 					}
-				}
 					
-				IList<MemberInfo> itemTypeMembers = gridValuesProvider.GetItemTypeMembers();
-				InitializeColumns((GridView)this.listView.View, itemTypeMembers);
-				this.columnHider = new GridViewColumnHider((GridView)this.listView.View);
-				cmbColumns.ItemsSource = this.columnHider.HideableColumns;
+					IList<MemberInfo> itemTypeMembers = gridValuesProvider.GetItemTypeMembers();
+					InitializeColumns((GridView)this.listView.View, itemTypeMembers);
+					this.columnHider = new GridViewColumnHider((GridView)this.listView.View);
+					cmbColumns.ItemsSource = this.columnHider.HideableColumns;
+				}
+			} catch (GetValueException ex) {
+				// TODO display ex msg
+			} catch (DebuggerVisualizerException ex) {
+				// TODO display ex msg
 			}
 		}
 		
-		ListValuesProvider CreateListValuesProvider(ICSharpCode.NRefactory.Ast.Expression targetObject, DebugType iListType, DebugType listItemType)
+		ListValuesProvider CreateListValuesProvider(Value targetValue, DebugType iListType, DebugType listItemType)
 		{
-			var listValuesProvider = new ListValuesProvider(targetObject, iListType, listItemType);
+			var listValuesProvider = new ListValuesProvider(targetValue, listItemType);
 			var virtCollection = new VirtualizingCollection<ObjectValue>(listValuesProvider);
 			this.listView.ItemsSource = virtCollection;
 			return listValuesProvider;

src/AddIns/Debugger/Debugger.AddIn/Visualizers/GridVisualizer/ObjectValue.cs

@@ -16,14 +16,10 @@ namespace Debugger.AddIn.Visualizers.GridVisualizer
 	/// </summary>
 	public class ObjectValue
 	{
-		private int index;
 		/// <summary> Index of this item in the collection. </summary>
-		public int Index {
-			get { return index; }
-		}
+		public int Index { get; private set; }
 		
-		// PermanentReference to one row. Even if we used expressions, they are cached using PermanentReferences, so
-		// one PermanentReference for a row would be created anyway
+		// PermanentReference for one row.
 		public Value PermanentReference { get; private set; }
 		
 		private Dictionary<string, ObjectProperty> properties = new Dictionary<string, ObjectProperty>();
@@ -33,7 +29,7 @@ namespace Debugger.AddIn.Visualizers.GridVisualizer
 		
 		internal ObjectValue(int index, Dictionary<string, MemberInfo> memberFromNameMap)
 		{
-			this.index = index;
+			this.Index = index;
 			this.memberForNameMap = memberFromNameMap;
 		}
 
@@ -60,7 +56,6 @@ namespace Debugger.AddIn.Visualizers.GridVisualizer
 				}
 				return property;
 			}
-			//set	{ properties[key] = value; }
 		}
 		
 		public static ObjectValue Create(Debugger.Value value, int index, Dictionary<string, MemberInfo> memberFromName)