diff --git a/Editor/Controls/CharacterToolBar.axaml.cs b/Editor/Controls/CharacterToolBar.axaml.cs
index 65a4c91..b9a9340 100644
--- a/Editor/Controls/CharacterToolBar.axaml.cs
+++ b/Editor/Controls/CharacterToolBar.axaml.cs
@@ -37,7 +37,7 @@ private void ToolBarButton_PointerEntered(object? sender, PointerEventArgs e)
         }
     }
 
-    private void ToolBarButton_GotFocus(object? sender, GotFocusEventArgs e)
+    private void ToolBarButton_GotFocus(object? sender, FocusChangedEventArgs e)
     {
         if (sender is Button)
         {
diff --git a/Editor/Controls/EquationToolBar.axaml.cs b/Editor/Controls/EquationToolBar.axaml.cs
index 2e22f64..d444c0c 100644
--- a/Editor/Controls/EquationToolBar.axaml.cs
+++ b/Editor/Controls/EquationToolBar.axaml.cs
@@ -39,7 +39,7 @@ private void ToolBarButton_PointerEntered(object? sender, PointerEventArgs e)
         }
     }
 
-    private void ToolBarButton_GotFocus(object? sender, GotFocusEventArgs e)
+    private void ToolBarButton_GotFocus(object? sender, FocusChangedEventArgs e)
     {
         if (sender is Button)
         {
diff --git a/Editor/Editor.csproj b/Editor/Editor.csproj
index 7b21061..0985930 100644
--- a/Editor/Editor.csproj
+++ b/Editor/Editor.csproj
@@ -18,9 +18,9 @@
   </ItemGroup>
   
   <ItemGroup>
-    <PackageReference Include="Avalonia" Version="11.3.13" />
-    <PackageReference Include="Avalonia.AvaloniaEdit" Version="11.4.1" />
-    <PackageReference Include="AvaloniaEdit.TextMate" Version="11.4.1" />
+    <PackageReference Include="Avalonia" Version="12.0.0" />
+    <PackageReference Include="Avalonia.AvaloniaEdit" Version="12.0.0" />
+    <PackageReference Include="AvaloniaEdit.TextMate" Version="12.0.0" />
     <PackageReference Condition="'$(Configuration)' == 'Debug'" Include="Avalonia.Diagnostics" Version="11.3.13" />
     <PackageReference Include="Clowd.Clipboard.Avalonia" Version="1.1.4" />
     <PackageReference Include="CommunityToolkit.Mvvm" Version="8.4.2" />
diff --git a/Editor/Interfaces/IMainWindow.cs b/Editor/Interfaces/IMainWindow.cs
index 28feb85..76a0963 100644
--- a/Editor/Interfaces/IMainWindow.cs
+++ b/Editor/Interfaces/IMainWindow.cs
@@ -10,7 +10,7 @@ public interface IMainWindow
 
     TopLevel TopLevel { get; }
     WindowState WindowState { get; set; }
-    SystemDecorations SystemDecorations { get; set; }
+    WindowDecorations WindowDecorations { get; set; }
     bool ContentDialogShown { get; }
     bool IsSelecting { get; set; }
     bool IsEditorLoaded { get; }
diff --git a/Editor/ViewModels/MainWindowViewModel.cs b/Editor/ViewModels/MainWindowViewModel.cs
index 1cee8f0..62abf52 100644
--- a/Editor/ViewModels/MainWindowViewModel.cs
+++ b/Editor/ViewModels/MainWindowViewModel.cs
@@ -26,7 +26,7 @@ public partial class MainWindowViewModel : ObservableObject, ICultureInfoChanged
     private MenuItem _recentFileItem = null!;
 
     private WindowState _windowState;
-    private SystemDecorations _systemDecorations;
+    private WindowDecorations _windowDecorations;
     private bool _fullScreenModeEntered;
     private readonly Lock _fullScreenModeLock = new();
 
@@ -353,9 +353,9 @@ public void EnterFullScreen()
             if (_fullScreenModeEntered) return;
 
             _windowState = MainWindow.WindowState;
-            _systemDecorations = MainWindow.SystemDecorations;
+            _windowDecorations = MainWindow.WindowDecorations;
             MainWindow.WindowState = WindowState.FullScreen;
-            MainWindow.SystemDecorations = SystemDecorations.None;
+            MainWindow.WindowDecorations = WindowDecorations.None;
 
             _fullScreenModeEntered = true;
         }
@@ -373,7 +373,7 @@ public void ExitFullScreen(WindowState windowState)
             if (!_fullScreenModeEntered) return;
 
             MainWindow.WindowState = windowState;
-            MainWindow.SystemDecorations = _systemDecorations;
+            MainWindow.WindowDecorations = _windowDecorations;
 
             _fullScreenModeEntered = false;
         }
diff --git a/Editor/ViewModels/UnicodeSelectorWindowViewModel.cs b/Editor/ViewModels/UnicodeSelectorWindowViewModel.cs
index a952b25..c1c46fb 100644
--- a/Editor/ViewModels/UnicodeSelectorWindowViewModel.cs
+++ b/Editor/ViewModels/UnicodeSelectorWindowViewModel.cs
@@ -130,8 +130,12 @@ private static bool TypefaceContainsCharacter(Typeface typeface, char characterT
         try
         {
             var glyphTypeface = typeface.GlyphTypeface;
-            uint codepoint = characterToCheck;
-            return glyphTypeface.TryGetGlyph(codepoint, out _);
+            int codepoint = characterToCheck;
+            if (glyphTypeface.CharacterToGlyphMap.TryGetGlyph(codepoint, out ushort glyphIndex))
+            {
+                return glyphIndex > 0;
+            }
+            return false;
         }
         catch (Exception e)
         {
diff --git a/README.md b/README.md
index 50e35e7..92c75f8 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@
 Open-source, cross-platform equation editor built with Avalonia. A modern, free alternative to MathType for creating mathematical and scientific documents.
 
 - Cross-platform: Windows, macOS, and Linux
-- Fast desktop UI: Avalonia 11
+- Fast desktop UI: Avalonia 12
 - Modern .NET: .NET 10
 - Open source: MIT licensed