New and improved DevTools.

build/CoreLibraries.props

@@ -4,7 +4,6 @@
       <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.Animation/Avalonia.Animation.csproj" />
       <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.Controls/Avalonia.Controls.csproj" />
       <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.DesignerSupport/Avalonia.DesignerSupport.csproj" />
-      <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.Diagnostics/Avalonia.Diagnostics.csproj" />
       <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.Input/Avalonia.Input.csproj" />
       <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.Interactivity/Avalonia.Interactivity.csproj" />
       <ProjectReference Include="$(MSBuildThisFileDirectory)/../src/Avalonia.Layout/Avalonia.Layout.csproj" />

samples/BindingDemo/BindingDemo.csproj

@@ -4,6 +4,7 @@
     <TargetFrameworks>netcoreapp2.0;net461</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
+    <ProjectReference Include="..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />
     <ProjectReference Include="..\..\src\Linux\Avalonia.LinuxFramebuffer\Avalonia.LinuxFramebuffer.csproj" />
     <ProjectReference Include="..\..\src\Avalonia.ReactiveUI\Avalonia.ReactiveUI.csproj" />
   </ItemGroup>

samples/ControlCatalog/ControlCatalog.csproj

@@ -21,6 +21,7 @@
 
   <ItemGroup>
     <ProjectReference Include="..\..\packages\Avalonia\Avalonia.csproj" />
+    <ProjectReference Include="..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />
     <ProjectReference Include="..\..\src\Avalonia.ReactiveUI\Avalonia.ReactiveUI.csproj" />
     <ProjectReference Include="..\..\src\Avalonia.Controls.DataGrid\Avalonia.Controls.DataGrid.csproj" />
   </ItemGroup>

samples/RenderDemo/RenderDemo.csproj

@@ -4,6 +4,7 @@
     <TargetFrameworks>netcoreapp2.0;net461</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
+    <ProjectReference Include="..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />
     <ProjectReference Include="..\..\src\Linux\Avalonia.LinuxFramebuffer\Avalonia.LinuxFramebuffer.csproj" />
     <ProjectReference Include="..\..\src\Avalonia.ReactiveUI\Avalonia.ReactiveUI.csproj" />
   </ItemGroup>

samples/VirtualizationDemo/VirtualizationDemo.csproj

@@ -4,6 +4,7 @@
     <TargetFrameworks>netcoreapp2.0;net461</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
+    <ProjectReference Include="..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />
     <ProjectReference Include="..\..\src\Linux\Avalonia.LinuxFramebuffer\Avalonia.LinuxFramebuffer.csproj" />
     <ProjectReference Include="..\..\src\Avalonia.ReactiveUI\Avalonia.ReactiveUI.csproj" />
   </ItemGroup>

src/Avalonia.Base/ValueStore.cs

@@ -173,7 +173,7 @@ public void CoerceValue<T>(StyledPropertyBase<T> property)
             {
                 return new Diagnostics.AvaloniaPropertyValue(
                     property,
-                    slot.Value.HasValue ? (object)slot.Value : AvaloniaProperty.UnsetValue,
+                    slot.Value.HasValue ? slot.Value.Value : AvaloniaProperty.UnsetValue,
                     slot.ValuePriority,
                     null);
             }

src/Avalonia.Diagnostics/Avalonia.Diagnostics.csproj

@@ -1,8 +1,15 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
+    <RootNamespace>Avalonia</RootNamespace>
   </PropertyGroup>
   <ItemGroup>
+    <Compile Update="**\*.xaml.cs">
+      <DependentUpon>%(Filename)</DependentUpon>
+    </Compile>
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\Avalonia.Controls.DataGrid\Avalonia.Controls.DataGrid.csproj" />
     <ProjectReference Include="..\Markup\Avalonia.Markup.Xaml\Avalonia.Markup.Xaml.csproj" />
     <ProjectReference Include="..\Markup\Avalonia.Markup\Avalonia.Markup.csproj" />
     <ProjectReference Include="..\Avalonia.Animation\Avalonia.Animation.csproj" />
@@ -14,7 +21,10 @@
     <ProjectReference Include="..\Avalonia.Visuals\Avalonia.Visuals.csproj" />
     <ProjectReference Include="..\Avalonia.Styling\Avalonia.Styling.csproj" />
     <ProjectReference Include="..\Avalonia.Themes.Default\Avalonia.Themes.Default.csproj" />
-  </ItemGroup>  
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Scripting" Version="3.4.0" />
+  </ItemGroup>
   <Import Project="..\..\build\EmbedXaml.props" />
   <Import Project="..\..\build\Rx.props" />
   <Import Project="..\..\build\BuildTargets.targets" />

src/Avalonia.Diagnostics/DevToolsExtensions.cs

@@ -0,0 +1,19 @@
+using Avalonia.Controls;
+using Avalonia.Diagnostics;
+using Avalonia.Input;
+
+namespace Avalonia
+{
+    public static class DevToolsExtensions
+    {
+        public static void AttachDevTools(this TopLevel root)
+        {
+            DevTools.Attach(root, new KeyGesture(Key.F12));
+        }
+
+        public static void AttachDevTools(this TopLevel root, KeyGesture gesture)
+        {
+            DevTools.Attach(root, gesture);
+        }
+    }
+}

src/Avalonia.Diagnostics/Diagnostics/Converters/BoolToBrushConverter.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Globalization;
+using Avalonia.Data.Converters;
+using Avalonia.Media;
+
+namespace Avalonia.Diagnostics.Converters
+{
+    internal class BoolToBrushConverter : IValueConverter
+    {
+        public IBrush Brush { get; set; }
+
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            return (bool)value ? Brush : Brushes.Transparent;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

src/Avalonia.Diagnostics/Diagnostics/DevTools.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Collections.Generic;
+using System.Reactive.Disposables;
+using Avalonia.Controls;
+using Avalonia.Diagnostics.Views;
+using Avalonia.Input;
+using Avalonia.Interactivity;
+
+namespace Avalonia.Diagnostics
+{
+    public static class DevTools
+    {
+        private static readonly Dictionary<TopLevel, Window> s_open = new Dictionary<TopLevel, Window>();
+
+        public static IDisposable Attach(TopLevel root, KeyGesture gesture)
+        {
+            void PreviewKeyDown(object sender, KeyEventArgs e)
+            {
+                if (gesture.Matches(e))
+                {
+                    Open(root);
+                }
+            }
+
+            return root.AddHandler(
+                InputElement.KeyDownEvent,
+                PreviewKeyDown,
+                RoutingStrategies.Tunnel);
+        }
+
+        public static IDisposable Open(TopLevel root)
+        {
+            if (s_open.TryGetValue(root, out var window))
+            {
+                window.Activate();
+            }
+            else
+            {
+                window = new MainWindow
+                {
+                    Width = 1024,
+                    Height = 512,
+                    Root = root,
+                };
+
+                window.Closed += DevToolsClosed;
+                s_open.Add(root, window);
+                window.Show();
+            }
+
+            return Disposable.Create(() => window?.Close());
+        }
+
+        private static void DevToolsClosed(object sender, EventArgs e)
+        {
+            var window = (MainWindow)sender;
+            s_open.Remove(window.Root);
+            window.Closed -= DevToolsClosed;
+        }
+    }
+}