[Debugger] Fixed CanRename() logic for Locals/Watch context menu & allowed disabled menu items

Author: jstedfast

main/src/addins/MonoDevelop.Debugger/MonoDevelop.Debugger/ObjectValue/Mac/MacObjectValueTreeView.cs

@@ -913,7 +913,7 @@ protected void OnUpdateAddWatch (CommandInfo cinfo)
 		[CommandHandler (EditCommands.Rename)]
 		protected void OnRename ()
 		{
-			if (SelectedRow == -1)
+			if (SelectedRowCount != 1 || SelectedRow < 0)
 				return;
 
 			var nameView = (MacDebuggerObjectNameView) GetView (0, SelectedRow, false);
@@ -928,7 +928,13 @@ void OnRename (object sender, EventArgs args)
 
 		bool CanRename (out bool enabled)
 		{
-			enabled = SelectedRowCount == 1 && SelectedRow != -1;
+			if (SelectedRowCount == 1 && SelectedRow >= 0) {
+				var item = (MacObjectValueNode) ItemAtRow (SelectedRow);
+
+				enabled = item.Target.Parent is RootObjectValueNode || item.Target is AddNewExpressionObjectValueNode;
+			} else {
+				enabled = false;
+			}
 
 			return AllowWatchExpressions;
 		}
@@ -951,7 +957,9 @@ public override NSMenu MenuForEvent (NSEvent theEvent)
 			if (row < 0)
 				return null;
 
-			var menu = new NSMenu ();
+			var menu = new NSMenu {
+				AutoEnablesItems = false
+			};
 			bool enabled;
 
 			if (CanAddWatch (out enabled)) {