Rewrite editor navigation model

Bonsai.Editor.Tests/MockGraphView.cs

@@ -18,6 +18,7 @@ public MockGraphView(ExpressionBuilderGraph workflow = null)
             Workflow = workflow ?? new ExpressionBuilderGraph();
             CommandExecutor = new CommandExecutor();
             var serviceContainer = new ServiceContainer();
+            serviceContainer.AddService(typeof(WorkflowBuilder), new WorkflowBuilder(Workflow));
             serviceContainer.AddService(typeof(CommandExecutor), CommandExecutor);
             ServiceProvider = serviceContainer;
         }

Bonsai.Editor.Tests/WorkflowEditorTests.cs

@@ -51,7 +51,6 @@ static string ToString(IEnumerable<T> sequence)
             var editor = new WorkflowEditor(graphView.ServiceProvider, graphView);
             editor.UpdateLayout.Subscribe(graphView.UpdateGraphLayout);
             editor.UpdateSelection.Subscribe(graphView.UpdateSelection);
-            editor.Workflow = graphView.Workflow;
 
             var nodeSequence = editor.GetGraphValues().ToArray();
             return (editor, assertIsReversible: () =>

Bonsai.Editor/EditorSettings.cs

@@ -21,6 +21,7 @@ sealed class EditorSettings
         internal EditorSettings(string path)
         {
             AnnotationPanelSize = 400;
+            ExplorerSplitterDistance = 300;
             settingsPath = path;
         }
 
@@ -37,6 +38,8 @@ public static EditorSettings Instance
 
         public int AnnotationPanelSize { get; set; }
 
+        public int ExplorerSplitterDistance { get; set; }
+
         public RecentlyUsedFileCollection RecentlyUsedFiles
         {
             get { return recentlyUsedFiles; }
@@ -74,6 +77,11 @@ static EditorSettings Load()
                                 int.TryParse(reader.ReadElementContentAsString(), out int annotationPanelSize);
                                 settings.AnnotationPanelSize = annotationPanelSize;
                             }
+                            else if (reader.Name == nameof(ExplorerSplitterDistance))
+                            {
+                                int.TryParse(reader.ReadElementContentAsString(), out int explorerSplitterDistance);
+                                settings.ExplorerSplitterDistance = explorerSplitterDistance;
+                            }
                             else if (reader.Name == nameof(DesktopBounds))
                             {
                                 reader.ReadToFollowing(nameof(Rectangle.X));
@@ -120,6 +128,7 @@ public void Save()
                 writer.WriteElementString(nameof(WindowState), WindowState.ToString());
                 writer.WriteElementString(nameof(EditorTheme), EditorTheme.ToString());
                 writer.WriteElementString(nameof(AnnotationPanelSize), AnnotationPanelSize.ToString(CultureInfo.InvariantCulture));
+                writer.WriteElementString(nameof(ExplorerSplitterDistance), ExplorerSplitterDistance.ToString(CultureInfo.InvariantCulture));
 
                 writer.WriteStartElement(nameof(DesktopBounds));
                 writer.WriteElementString(nameof(Rectangle.X), DesktopBounds.X.ToString(CultureInfo.InvariantCulture));