Minor fixes on windows

src/PixiDocks

@@ -1 +1 @@
-Subproject commit 33b8151ed96501ea5f91fd6b2f222c1bef7322d4
+Subproject commit a471122b4b973ebd7d5730a4f5dfb68908ebf423

src/PixiEditor/ViewModels/Menu/MenuBarViewModel.cs

@@ -110,6 +110,7 @@ internal class MenuBarViewModel : PixiObservableObject
         MenuItem? parent = null)
     {
         string? lastSubCommand = null;
+        MenuEntries ??= new ObservableCollection<MenuItem>();
 
         foreach (var item in root)
         {

src/PixiEditor/Views/Dialogs/DialogTitleBar.axaml

@@ -21,7 +21,7 @@
             FontSize="13"
             Margin="5,0,0,0"/>
         <DockPanel IsHitTestVisible="True">
-            <CaptionButtons Name="captionButtons" DockPanel.Dock="Right" IsVisible="{OnPlatform macOS=false}"/>
+            <CaptionButtons Name="captionButtons" DockPanel.Dock="Right" IsVisible="{OnPlatform macOS=false, Default=true}"/>
             <ContentPresenter DockPanel.Dock="Right" IsVisible="{Binding !!AdditionalElement}" Content="{Binding Path=AdditionalElement}"/>
             <Control /><!-- dummy control to occupy dockpanel center -->
         </DockPanel>

src/PixiEditor/Views/Main/MainTitleBar.axaml

@@ -50,7 +50,7 @@
                     </OnPlatform.macOS>
                 </OnPlatform>
             </StackPanel.Margin>
-            <xaml:Menu IsVisible="{OnPlatform macOS=false}"
+            <xaml:Menu IsVisible="{OnPlatform macOS=false, Default=true}"
                        Margin="40, 0, 0, 0"
                        DockPanel.Dock="Left"
                        HorizontalAlignment="Left"

src/PixiEditor/Views/Main/MainTitleBar.axaml.cs

@@ -1,6 +1,7 @@
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Markup.Xaml;
+using PixiEditor.OperatingSystem;
 using PixiEditor.ViewModels.Menu;
 
 namespace PixiEditor.Views.Main;
@@ -20,7 +21,7 @@ public partial class MainTitleBar : UserControl {
     protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
     {
         base.OnAttachedToVisualTree(e);
-        if (DataContext is MenuBarViewModel menuBarViewModel)
+        if (IOperatingSystem.Current.IsMacOs && DataContext is MenuBarViewModel menuBarViewModel)
         {
             NativeMenu.SetMenu(MainWindow.Current, menuBarViewModel.NativeMenu);
         }