Fix Browser theme MDI chrome and split drops

samples/BrowserTabTheme/App.axaml.cs

@@ -10,6 +10,8 @@ namespace BrowserTabTheme;
 
 public partial class App : Application
 {
+    private MainWindowViewModel? _mainWindowViewModel;
+
     public override void Initialize()
     {
 #if DOCK_USE_GENERATED_APP_INITIALIZE_COMPONENT
@@ -66,15 +68,21 @@ public override void OnFrameworkInitializationCompleted()
 
             factory.InitLayout(rootDock);
 
-            var mainWindow = new MainWindow();
-            mainWindow.DockControl.Factory = factory;
-            mainWindow.DockControl.Layout = rootDock;
-            mainWindow.DockControl.InitializeFactory = true;
-            mainWindow.DockControl.InitializeLayout = false;
-
+            _mainWindowViewModel = new MainWindowViewModel(factory, rootDock);
+            var mainWindow = new MainWindow
+            {
+                DataContext = _mainWindowViewModel
+            };
             desktop.MainWindow = mainWindow;
+            desktop.Exit += (_, _) => DisposeMainWindowViewModel();
         }
 
         base.OnFrameworkInitializationCompleted();
     }
+
+    private void DisposeMainWindowViewModel()
+    {
+        _mainWindowViewModel?.Dispose();
+        _mainWindowViewModel = null;
+    }
 }

samples/BrowserTabTheme/BrowserTabTheme.csproj

@@ -16,6 +16,7 @@
   <Import Project="..\..\build\Avalonia.props" />
   <Import Project="..\..\build\Avalonia.Themes.Fluent.props" />
   <Import Project="..\..\build\Avalonia.Desktop.props" />
+  <Import Project="..\..\build\Avalonia.ReactiveUI.props" />
 
   <ItemGroup>
     <ProjectReference Include="..\..\src\Dock.Model\Dock.Model.csproj" />
@@ -25,5 +26,11 @@
     <ProjectReference Include="..\..\src\Dock.Avalonia.Themes.Fluent\Dock.Avalonia.Themes.Fluent.csproj" />
   </ItemGroup>
 
-</Project>
+  <ItemGroup>
+    <PackageReference Include="ReactiveUI.SourceGenerators">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
 
+</Project>

samples/BrowserTabTheme/MainWindow.axaml

@@ -1,13 +1,20 @@
 <Window xmlns="https://github.com/avaloniaui"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="using:BrowserTabTheme"
         x:Class="BrowserTabTheme.MainWindow"
+        x:DataType="vm:MainWindowViewModel"
         Title="BrowserTabTheme Sample"
         Width="1300"
         Height="820"
         Background="{DynamicResource DockSurfaceHeaderBrush}"
-        ExtendClientAreaToDecorationsHint="True"
+        ExtendClientAreaToDecorationsHint="{CompiledBinding ExtendClientAreaToDecorationsHint}"
         ExtendClientAreaTitleBarHeightHint="-1"
         >
-  <DockControl Name="DockControl" Margin="6" />
+  <DockControl Name="DockControl"
+               Margin="6"
+               Factory="{CompiledBinding Factory}"
+               Layout="{CompiledBinding Layout}"
+               InitializeFactory="True"
+               InitializeLayout="False" />
 
 </Window>

samples/BrowserTabTheme/MainWindowViewModel.cs

@@ -0,0 +1,155 @@
+// Copyright (c) Wiesław Šoltés. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for details.
+
+using System;
+using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.ComponentModel;
+using Dock.Model.Controls;
+using Dock.Model.Core;
+using ReactiveUI;
+using ReactiveUI.SourceGenerators;
+
+namespace BrowserTabTheme;
+
+/// <summary>
+/// Coordinates the browser sample layout and its main-window chrome state.
+/// </summary>
+public sealed partial class MainWindowViewModel : ReactiveObject, IDisposable
+{
+    private readonly HashSet<IDocumentDock> _documentDocks = new();
+    private readonly HashSet<INotifyCollectionChanged> _dockCollections = new();
+    private bool _isDisposed;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="MainWindowViewModel"/> class.
+    /// </summary>
+    /// <param name="factory">The layout factory.</param>
+    /// <param name="layout">The main root layout.</param>
+    public MainWindowViewModel(IFactory factory, IRootDock layout)
+    {
+        Factory = factory ?? throw new ArgumentNullException(nameof(factory));
+        Layout = layout ?? throw new ArgumentNullException(nameof(layout));
+        ExtendClientAreaToDecorationsHint = true;
+        RefreshSubscriptions();
+    }
+
+    /// <summary>
+    /// Gets the layout factory used by the dock control.
+    /// </summary>
+    public IFactory Factory { get; }
+
+    /// <summary>
+    /// Gets the main root layout.
+    /// </summary>
+    public IRootDock Layout { get; }
+
+    /// <summary>
+    /// Gets whether content should extend into the main window decorations.
+    /// </summary>
+    [Reactive]
+    public partial bool ExtendClientAreaToDecorationsHint { get; private set; }
+
+    /// <inheritdoc/>
+    public void Dispose()
+    {
+        if (_isDisposed)
+        {
+            return;
+        }
+
+        _isDisposed = true;
+        ClearSubscriptions();
+    }
+
+    private void RefreshSubscriptions()
+    {
+        ClearSubscriptions();
+
+        var pending = new Stack<IDockable>();
+        var visited = new HashSet<IDockable>();
+        pending.Push(Layout);
+
+        while (pending.Count > 0)
+        {
+            var dockable = pending.Pop();
+            if (!visited.Add(dockable))
+            {
+                continue;
+            }
+
+            if (dockable is IDocumentDock documentDock)
+            {
+                _documentDocks.Add(documentDock);
+                if (documentDock is INotifyPropertyChanged notifyingDocumentDock)
+                {
+                    notifyingDocumentDock.PropertyChanged += OnDocumentDockPropertyChanged;
+                }
+            }
+
+            if (dockable is not IDock { VisibleDockables: { } visibleDockables })
+            {
+                continue;
+            }
+
+            if (visibleDockables is INotifyCollectionChanged notifyingCollection
+                && _dockCollections.Add(notifyingCollection))
+            {
+                notifyingCollection.CollectionChanged += OnDockCollectionChanged;
+            }
+
+            for (var index = visibleDockables.Count - 1; index >= 0; index--)
+            {
+                pending.Push(visibleDockables[index]);
+            }
+        }
+
+        UpdateChromeState();
+    }
+
+    private void ClearSubscriptions()
+    {
+        foreach (var documentDock in _documentDocks)
+        {
+            if (documentDock is INotifyPropertyChanged notifyingDocumentDock)
+            {
+                notifyingDocumentDock.PropertyChanged -= OnDocumentDockPropertyChanged;
+            }
+        }
+
+        foreach (var dockCollection in _dockCollections)
+        {
+            dockCollection.CollectionChanged -= OnDockCollectionChanged;
+        }
+
+        _documentDocks.Clear();
+        _dockCollections.Clear();
+    }
+
+    private void OnDockCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
+    {
+        RefreshSubscriptions();
+    }
+
+    private void OnDocumentDockPropertyChanged(object? sender, PropertyChangedEventArgs e)
+    {
+        if (string.IsNullOrEmpty(e.PropertyName) || e.PropertyName == nameof(IDocumentDock.LayoutMode))
+        {
+            UpdateChromeState();
+        }
+    }
+
+    private void UpdateChromeState()
+    {
+        foreach (var documentDock in _documentDocks)
+        {
+            if (documentDock.LayoutMode == DocumentLayoutMode.Mdi)
+            {
+                ExtendClientAreaToDecorationsHint = false;
+                return;
+            }
+        }
+
+        ExtendClientAreaToDecorationsHint = true;
+    }
+}

samples/BrowserTabTheme/README.md

@@ -6,7 +6,11 @@ This sample backports a browser-tab visual style from StackWich into the origina
 
 - Browser-like document and tool tab visuals.
 - Browser-style window chrome driven by Avalonia drawn decorations and Dock theme resources.
-- Dock drag/drop, float, pin, and document creation behavior preserved.
+- Dock drag/drop, including dropping a tab onto a side target to create a new
+  horizontal or vertical document dock.
+- Native main-window chrome while document layout mode is MDI, keeping maximized
+  MDI children clear of the operating-system caption controls.
+- Float, pin, and document creation behavior preserved.
 - Theme dictionaries for both Light (`Default`) and Dark variants.
 
 ## What is intentionally excluded

src/Dock.Avalonia.Themes.Browser/Styles/BrowserTabAccents.axaml

@@ -165,7 +165,9 @@
   <x:Boolean x:Key="DockDocumentTabStripHideWhenEmpty">False</x:Boolean>
   <x:Boolean x:Key="DockDocumentTabStripToggleWindowStateOnDoubleTap">True</x:Boolean>
   <x:Boolean x:Key="DockDocumentControlTabStripVisible">True</x:Boolean>
-  <x:Boolean x:Key="DockDocumentControlShowDockIndicatorOnly">True</x:Boolean>
+  <!-- Keep the full local selector available so a tab can be dropped into a
+       newly created horizontal or vertical document dock. -->
+  <x:Boolean x:Key="DockDocumentControlShowDockIndicatorOnly">False</x:Boolean>
   <x:Boolean x:Key="DockDocumentTabStripSeparatorVisible">False</x:Boolean>
   <sys:Double x:Key="DockDocumentControlVerticalSpacing">6</sys:Double>
   <StaticResource x:Key="DockDocumentContentBorderBrush" ResourceKey="DockBorderSubtleBrush" />

tests/Dock.Avalonia.HeadlessTests/BrowserTabThemeMainWindowViewModelTests.cs

@@ -0,0 +1,49 @@
+// Copyright (c) Wiesław Šoltés. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for details.
+
+using BrowserTabTheme;
+using Dock.Model.Controls;
+using Dock.Model.Core;
+using Dock.Model.Mvvm;
+using Xunit;
+
+namespace Dock.Avalonia.HeadlessTests;
+
+public class BrowserTabThemeMainWindowViewModelTests
+{
+    [Fact]
+    public void ChromeStateTracksAllCurrentDocumentDocks()
+    {
+        var factory = new Factory();
+        var root = factory.CreateRootDock();
+        root.VisibleDockables = factory.CreateList<IDockable>();
+        var proportionalDock = factory.CreateProportionalDock();
+        proportionalDock.VisibleDockables = factory.CreateList<IDockable>();
+        var firstDocumentDock = factory.CreateDocumentDock();
+        firstDocumentDock.VisibleDockables = factory.CreateList<IDockable>();
+
+        factory.AddDockable(proportionalDock, firstDocumentDock);
+        factory.AddDockable(root, proportionalDock);
+        factory.InitLayout(root);
+
+        using var viewModel = new MainWindowViewModel(factory, root);
+
+        Assert.True(viewModel.ExtendClientAreaToDecorationsHint);
+
+        var secondDocumentDock = factory.CreateDocumentDock();
+        secondDocumentDock.VisibleDockables = factory.CreateList<IDockable>();
+        factory.AddDockable(proportionalDock, secondDocumentDock);
+        secondDocumentDock.LayoutMode = DocumentLayoutMode.Mdi;
+
+        Assert.False(viewModel.ExtendClientAreaToDecorationsHint);
+
+        firstDocumentDock.LayoutMode = DocumentLayoutMode.Mdi;
+        factory.RemoveDockable(secondDocumentDock, false);
+
+        Assert.False(viewModel.ExtendClientAreaToDecorationsHint);
+
+        firstDocumentDock.LayoutMode = DocumentLayoutMode.Tabbed;
+
+        Assert.True(viewModel.ExtendClientAreaToDecorationsHint);
+    }
+}

tests/Dock.Avalonia.HeadlessTests/Dock.Avalonia.HeadlessTests.csproj

@@ -16,6 +16,7 @@
   <Import Project="..\..\build\SignAssembly.props" />
 
   <ItemGroup>
+    <ProjectReference Include="..\..\samples\BrowserTabTheme\BrowserTabTheme.csproj" />
     <ProjectReference Include="..\..\src\Dock.Avalonia.Themes.Fluent\Dock.Avalonia.Themes.Fluent.csproj" />
     <ProjectReference Include="..\..\src\Dock.Avalonia.Themes.Simple\Dock.Avalonia.Themes.Simple.csproj" />
     <ProjectReference Include="..\..\src\Dock.Model\Dock.Model.csproj" />

tests/Dock.Avalonia.Themes.UnitTests/DocumentTabStripItemAndThemeTests.cs

@@ -1,6 +1,8 @@
+using Avalonia.Controls;
 using Avalonia.Headless.XUnit;
 using Avalonia.Styling;
 using Dock.Avalonia.Controls;
+using Dock.Avalonia.Themes.Browser;
 using Dock.Avalonia.Themes.Fluent;
 using Dock.Avalonia.Themes.Simple;
 using Xunit;
@@ -36,4 +38,17 @@ public void DockSimpleTheme_Can_Instantiate()
         Styles theme = new DockSimpleTheme();
         Assert.NotNull(theme);
     }
+
+    [AvaloniaFact]
+    public void BrowserTabTheme_Enables_Full_Document_Dock_Selector()
+    {
+        var theme = new BrowserTabTheme();
+        var resourceNode = Assert.IsAssignableFrom<IResourceNode>(theme);
+
+        Assert.True(resourceNode.TryGetResource(
+            "DockDocumentControlShowDockIndicatorOnly",
+            ThemeVariant.Default,
+            out var resource));
+        Assert.False(Assert.IsType<bool>(resource));
+    }
 }