adding the rest of the model for the tool for String editing.

src/Gen3Hex.Core/Gen3Hex.Core.csproj

@@ -60,7 +60,6 @@
     <Compile Include="ViewModels\IChildViewPort.cs" />
     <Compile Include="ViewModels\ITabContent.cs" />
     <Compile Include="ViewModels\IToolViewModel.cs" />
-    <Compile Include="ViewModels\IToolViewModel1.cs" />
     <Compile Include="ViewModels\IViewPort.cs" />
     <Compile Include="ViewModels\ScrollRegion.cs" />
     <Compile Include="ViewModels\SearchResultsViewPort.cs" />

src/Gen3Hex.Core/ViewModels/IToolViewModel.cs

@@ -1,8 +1,87 @@
-using System.Collections.Generic;
+using HavenSoft.Gen3Hex.Core.Models;
+using HavenSoft.Gen3Hex.Core.ViewModels.DataFormats;
+using System.Collections;
+using System.Collections.Generic;
 using System.ComponentModel;
+using System.Linq;
+using System.Windows.Input;
 
 namespace HavenSoft.Gen3Hex.Core.ViewModels {
    public interface IToolTrayViewModel : IReadOnlyList<IToolViewModel>, INotifyPropertyChanged {
       int SelectedIndex { get; set; }
+
+      PCSTool StringTool { get; }
+   }
+
+   public class ToolTray : ViewModelCore, IToolTrayViewModel {
+      private readonly IList<IToolViewModel> tools;
+      private readonly StubCommand stringToolCommand;
+
+      private int selectedIndex;
+      public int SelectedIndex {
+         get => selectedIndex;
+         set => TryUpdate(ref selectedIndex, value);
+      }
+
+      public int Count => tools.Count;
+      public IToolViewModel this[int index] => tools[index];
+      public PCSTool StringTool => (PCSTool)tools[0];
+      public ICommand StringToolCommand => stringToolCommand;
+
+      public ToolTray(IModel model) {
+         tools = new[] {
+            new PCSTool(model),
+         };
+
+         stringToolCommand = new StubCommand {
+            CanExecute = ICommandExtensions.CanAlwaysExecute,
+            Execute = arg => SelectedIndex = selectedIndex == 0 ? -1 : 0,
+         };
+
+         foreach (var tool in tools) tool.PropertyChanged += (sender, e) => SelectedIndex = tools.IndexOf((IToolViewModel)sender);
+         SelectedIndex = -1;
+      }
+
+      public IEnumerator<IToolViewModel> GetEnumerator() => tools.GetEnumerator();
+
+      IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+   }
+
+   public interface IToolViewModel : INotifyPropertyChanged {
+      string Name { get; }
+   }
+
+   public class PCSTool : ViewModelCore, IToolViewModel {
+      private readonly IModel model;
+      public string Name => "String";
+
+      private string content;
+      public string Content {
+         get => content;
+         set {
+            if (TryUpdate(ref content, value)) {
+               var run = model.GetNextRun(address) as PCSRun;
+               if (run == null) return;
+               var bytes = PCSString.Convert(content);
+               var newRun = model.RelocateForExpansion(run, bytes.Count);
+               for (int i = 0; i < bytes.Count; i++) model[newRun.Start + i] = bytes[i];
+               model.ObserveRunWritten(new PCSRun(newRun.Start, bytes.Count, newRun.PointerSources));
+            }
+         }
+      }
+
+      private int address = Pointer.NULL;
+      public int Address {
+         get => address;
+         set {
+            if (TryUpdate(ref address, value)) {
+               var run = model.GetNextRun(address) as PCSRun;
+               if (run == null) return;
+               TryUpdate(ref content, PCSString.Convert(model, run.Start, run.Length), nameof(Content));
+            }
+         }
+      }
+
+      public PCSTool(IModel model) => this.model = model;
    }
 }

src/Gen3Hex.Core/ViewModels/IToolViewModel1.cs

@@ -1,11 +0,0 @@
-using System.ComponentModel;
-
-namespace HavenSoft.Gen3Hex.Core.ViewModels {
-   public interface IToolViewModel : INotifyPropertyChanged {
-      string Name { get; }
-   }
-
-   public class PCSTool : ViewModelCore, IToolViewModel {
-      public string Name => "String";
-   }
-}

src/Gen3Hex.Core/ViewModels/ViewPort.cs

@@ -225,6 +225,7 @@ namespace HavenSoft.Gen3Hex.Core.ViewModels {
       public ViewPort(LoadedFile file, IModel model = null) {
          Model = model ?? new BasicModel(file.Contents);
          FileName = file.Name;
+         Tools = new ToolTray(Model);
 
          scroll = new ScrollRegion { DataLength = Model.Count };
          scroll.PropertyChanged += ScrollPropertyChanged;
@@ -442,6 +443,9 @@ namespace HavenSoft.Gen3Hex.Core.ViewModels {
                OnError(this, $"Pointer destination {pointer.DestinationName} not found.");
             }
          }
+         if (format is PCS pcs) {
+            Tools.StringTool.Address = pcs.Source;
+         }
       }
 
       public void ConsiderReload(IFileSystem fileSystem) {