Moved Menu into SplitView - Added Button to open SplitView

ViewModels/MainWindowViewModel.cs

@@ -1,4 +1,5 @@
-using Avalonia;
+using System;
+using Avalonia;
 using Avalonia.Input;
 using Avalonia.Media;
 using CommunityToolkit.Mvvm.Input;
@@ -11,6 +12,8 @@ public class MainWindowViewModel : ViewModelBase
 #pragma warning disable CA1822 // Mark members as static
     public MainWindowViewModel()
     {
+        DisplaySplitEvent = new RelayCommand(DisplaySplit);
+
         ColorPalette =
         [
             new ColorPickerButton

ViewModels/ViewModelBase.cs

@@ -1,4 +1,5 @@
-using System.Collections.ObjectModel;
+using System;
+using System.Collections.ObjectModel;
 using System.ComponentModel.DataAnnotations;
 using Avalonia.Input;
 using Avalonia.Media;
@@ -36,4 +37,26 @@ public class ViewModelBase : ObservableObject
         get => _brushThickness;
         set => SetProperty(ref _brushThickness, value);
     }
+
+    private double _buttonOffset = 0;
+
+    public double ButtonOffset
+    {
+        get => _buttonOffset;
+        set => SetProperty(ref _buttonOffset, value);
+    }
+
+    private bool _isSplitOpen = false;
+
+    public bool IsSplitOpen
+    {
+        get => _isSplitOpen;
+        set => SetProperty(ref _isSplitOpen, value);
+    }
+
+    public IRelayCommand DisplaySplitEvent { get; protected set; }
+    protected void DisplaySplit()
+    {
+        IsSplitOpen = !IsSplitOpen;
+    }
 }