DYN-6427 & DYN-6828 Graph Properties UI Fixes

src/GraphMetadataViewExtension/GraphMetadataViewModel.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.ObjectModel;
 using System.IO;
+using System.Linq;
 using System.Windows.Media.Imaging;
 using Dynamo.Core;
 using Dynamo.Graph.Workspaces;
@@ -130,19 +131,38 @@ public GraphMetadataViewModel(ViewLoadedParams viewLoadedParams, GraphMetadataVi
 
         private void OnCurrentWorkspaceChanged(Graph.Workspaces.IWorkspaceModel obj)
         {
+            //This event is triggered when a new workspace is opened or when the current workspace is cleared.
+            //This event manages state of the workspace properties (ie GraphDescription, GraphAuthor, HelpLink, Thumbnail)
+            //as well as the custom properties in the extension which do not live in the workspace model.
+
+            //Todo review if the workspace properties should be managed in the Workspace model.
+            //Do to the fact that Dynamo oftens leaves the workspace objs in memory and resets their properties when you open a new workspace
+            //the management of state is not straightforward. However it may make more sense to update those properteis with the clearing logic.
+
+            //Handle the case of a custom workspace model opening
             if (!(obj is HomeWorkspaceModel hwm))
             {
                 extension.Closed();
                 return;
             }
 
+            //Handle workspace change cases in UI.  First is a new workspace or template opening
+            //In this case the properties should be cleared
             if (!hwm.IsTemplate && string.IsNullOrEmpty(hwm.FileName) )
             {
                 GraphDescription = string.Empty;
                 GraphAuthor = string.Empty;
                 HelpLink = null;
                 Thumbnail = null;
             }
+            //Second is switching between an open workspace and open custom node and no state changes are required.
+            //This case can also be true if you close an open workspace while focused on a custom node.
+            //However in that scenario the first case will be triggered first due to empty filename.
+            else if(hwm == currentWorkspace)
+            {
+                return;
+            }
+            //Third is a new workspace opening from a saved file
             else
             {
                 currentWorkspace = hwm;
@@ -152,6 +172,7 @@ private void OnCurrentWorkspaceChanged(Graph.Workspaces.IWorkspaceModel obj)
                 RaisePropertyChanged(nameof(Thumbnail));
             }
 
+            //Clear custom properties for cases one and two.
             CustomProperties.Clear();
         }
 
@@ -216,8 +237,19 @@ private void OpenGraphStatusExecute(object obj)
 
         private void AddCustomPropertyExecute(object obj)
         {
-            var propName = Properties.Resources.CustomPropertyControl_CustomPropertyDefault + " " + (CustomProperties.Count + 1);
+            int increment = CustomProperties.Count + 1;
+            string propName = DefaultPropertyName(increment);
+
+            //Ensure the property name is unique
+            while (CustomProperties.Any(x => x.PropertyName == propName))
+            {
+                increment++;
+                propName = DefaultPropertyName(increment);
+            }
+
             AddCustomProperty(propName, string.Empty);
+
+            string DefaultPropertyName(int number) => Properties.Resources.CustomPropertyControl_CustomPropertyDefault + " " + number;
         }
 
         internal void AddCustomProperty(string propertyName, string propertyValue, bool markChange = true)