Fixed DevTools.

- Set `InheritanceParent` before Parent so that control doesn't
initially inherit the wrong DataContext
- Don't set `InheritanceParent` when setting `Parent` if
`InheritanceParent` already set
- Added `IDataTemplate.SupportsRecycling`

src/Avalonia.Controls/Control.cs

@@ -435,7 +435,11 @@ namespace Avalonia.Controls
                     OnDetachedFromLogicalTreeCore(e);
                 }
 
-                InheritanceParent = parent as AvaloniaObject;
+                if (InheritanceParent == null || parent == null)
+                {
+                    InheritanceParent = parent as AvaloniaObject;
+                }
+
                 _parent = (IControl)parent;
 
                 if (_parent is IStyleRoot || _parent?.IsAttachedToLogicalTree == true)

src/Avalonia.Controls/Presenters/ContentPresenter.cs

@@ -231,7 +231,10 @@ namespace Avalonia.Controls.Presenters
 
                 if (content != null)
                 {
-                    if (old != null && _dataTemplate?.Match(content) == true)
+                    if (old != null && 
+                        _dataTemplate != null &&
+                        _dataTemplate.SupportsRecycling && 
+                        _dataTemplate.Match(content))
                     {
                         result = old;
                     }
@@ -267,6 +270,8 @@ namespace Avalonia.Controls.Presenters
 
                 if (result != null)
                 {
+                    ((ISetInheritanceParent)result).SetParent(this);
+
                     Child = result;
 
                     if (result.Parent == null)
@@ -274,7 +279,6 @@ namespace Avalonia.Controls.Presenters
                         ((ISetLogicalParent)result).SetParent((ILogical)this.TemplatedParent ?? this);
                     }
 
-                    ((ISetInheritanceParent)result).SetParent(this);
                     VisualChildren.Add(result);
                 }
                 else

src/Avalonia.Controls/Templates/FuncDataTemplate.cs

@@ -31,7 +31,8 @@ namespace Avalonia.Controls.Templates
                     {
                         return null;
                     }
-                });
+                },
+                true);
 
         /// <summary>
         /// The implementation of the <see cref="Match"/> method.
@@ -45,8 +46,12 @@ namespace Avalonia.Controls.Templates
         /// <param name="build">
         /// A function which when passed an object of <paramref name="type"/> returns a control.
         /// </param>
-        public FuncDataTemplate(Type type, Func<object, IControl> build)
-            : this(o => IsInstance(o, type), build)
+        /// <param name="supportsRecycling">Whether the control can be recycled.</param>
+        public FuncDataTemplate(
+            Type type, 
+            Func<object, IControl> build,
+            bool supportsRecycling = false)
+            : this(o => IsInstance(o, type), build, supportsRecycling)
         {
         }
 
@@ -59,14 +64,22 @@ namespace Avalonia.Controls.Templates
         /// <param name="build">
         /// A function which returns a control for matching data.
         /// </param>
-        public FuncDataTemplate(Func<object, bool> match, Func<object, IControl> build)
+        /// <param name="supportsRecycling">Whether the control can be recycled.</param>
+        public FuncDataTemplate(
+            Func<object, bool> match,
+            Func<object, IControl> build,
+            bool supportsRecycling = false)
             : base(build)
         {
             Contract.Requires<ArgumentNullException>(match != null);
 
             _match = match;
+            SupportsRecycling = supportsRecycling;
         }
 
+        /// <inheritdoc/>
+        public bool SupportsRecycling { get; }
+
         /// <summary>
         /// Checks to see if this data template matches the specified data.
         /// </summary>

src/Avalonia.Controls/Templates/FuncDataTemplate`1.cs

@@ -17,8 +17,9 @@ namespace Avalonia.Controls.Templates
         /// <param name="build">
         /// A function which when passed an object of <typeparamref name="T"/> returns a control.
         /// </param>
-        public FuncDataTemplate(Func<T, IControl> build)
-            : base(typeof(T), CastBuild(build))
+        /// <param name="supportsRecycling">Whether the control can be recycled.</param>
+        public FuncDataTemplate(Func<T, IControl> build, bool supportsRecycling = false)
+            : base(typeof(T), CastBuild(build), supportsRecycling)
         {
         }
 
@@ -31,8 +32,12 @@ namespace Avalonia.Controls.Templates
         /// <param name="build">
         /// A function which when passed an object of <typeparamref name="T"/> returns a control.
         /// </param>
-        public FuncDataTemplate(Func<T, bool> match, Func<T, IControl> build)
-            : base(CastMatch(match), CastBuild(build))
+        /// <param name="supportsRecycling">Whether the control can be recycled.</param>
+        public FuncDataTemplate(
+            Func<T, bool> match,
+            Func<T, IControl> build,
+            bool supportsRecycling = false)
+            : base(CastMatch(match), CastBuild(build), supportsRecycling)
         {
         }
 

src/Avalonia.Controls/Templates/IDataTemplate.cs

@@ -8,6 +8,12 @@ namespace Avalonia.Controls.Templates
     /// </summary>
     public interface IDataTemplate : ITemplate<object, IControl>
     {
+        /// <summary>
+        /// Gets a value indicating whether the data template supports recycling of the generated
+        /// control.
+        /// </summary>
+        bool SupportsRecycling { get; }
+
         /// <summary>
         /// Checks to see if this data template matches the specified data.
         /// </summary>

src/Avalonia.Diagnostics/ViewLocator.cs

@@ -9,6 +9,8 @@ namespace Avalonia.Diagnostics
 {
     public class ViewLocator<TViewModel> : IDataTemplate
     {
+        public bool SupportsRecycling => false;
+
         public IControl Build(object data)
         {
             var name = data.GetType().FullName.Replace("ViewModel", "View");

src/Markup/Avalonia.Markup.Xaml/Templates/DataTemplate.cs

@@ -16,6 +16,8 @@ namespace Avalonia.Markup.Xaml.Templates
         [Content]
         public TemplateContent Content { get; set; }
 
+        public bool SupportsRecycling => true;
+
         public bool Match(object data)
         {
             if (DataType == null)

src/Markup/Avalonia.Markup.Xaml/Templates/TreeDataTemplate.cs

@@ -24,6 +24,8 @@ namespace Avalonia.Markup.Xaml.Templates
         [AssignBinding]
         public Binding ItemsSource { get; set; }
 
+        public bool SupportsRecycling => true;
+
         public bool Match(object data)
         {
             if (DataType == null)

tests/Avalonia.Controls.UnitTests/ControlTests.cs

@@ -22,22 +22,51 @@ namespace Avalonia.Controls.UnitTests
         }
 
         [Fact]
-        public void LogicalParent_Should_Be_Set_To_Parent()
+        public void Setting_Parent_Should_Also_Set_InheritanceParent()
         {
             var parent = new Decorator();
             var target = new TestControl();
 
             parent.Child = target;
 
+            Assert.Equal(parent, target.Parent);
             Assert.Equal(parent, target.InheritanceParent);
         }
 
         [Fact]
-        public void LogicalParent_Should_Be_Cleared_When_Removed_From_Parent()
+        public void Setting_Parent_Should_Not_Set_InheritanceParent_If_Already_Set()
         {
             var parent = new Decorator();
+            var inheritanceParent = new Decorator();
             var target = new TestControl();
 
+            ((ISetInheritanceParent)target).SetParent(inheritanceParent);
+            parent.Child = target;
+
+            Assert.Equal(parent, target.Parent);
+            Assert.Equal(inheritanceParent, target.InheritanceParent);
+        }
+
+        [Fact]
+        public void InheritanceParent_Should_Be_Cleared_When_Removed_From_Parent()
+        {
+            var parent = new Decorator();
+            var target = new TestControl();
+
+            parent.Child = target;
+            parent.Child = null;
+
+            Assert.Null(target.InheritanceParent);
+        }
+
+        [Fact]
+        public void InheritanceParent_Should_Be_Cleared_When_Removed_From_Parent_When_Has_Different_InheritanceParent()
+        {
+            var parent = new Decorator();
+            var inheritanceParent = new Decorator();
+            var target = new TestControl();
+
+            ((ISetInheritanceParent)target).SetParent(inheritanceParent);
             parent.Child = target;
             parent.Child = null;
 

tests/Avalonia.Controls.UnitTests/Presenters/ContentPresenterTests.cs

@@ -160,7 +160,7 @@ namespace Avalonia.Controls.UnitTests.Presenters
             {
                 DataTemplates = new DataTemplates
                 {
-                    new FuncDataTemplate<string>(_ => new Border()),
+                    new FuncDataTemplate<string>(_ => new Border(), true),
                 },
                 Content = "foo",
             };

tests/Avalonia.Controls.UnitTests/TreeViewTests.cs

@@ -462,6 +462,8 @@ namespace Avalonia.Controls.UnitTests
                 return new TextBlock { Text = node.Value };
             }
 
+            public bool SupportsRecycling => false;
+
             public InstancedBinding ItemsSelector(object item)
             {
                 var obs = new ExpressionObserver(item, nameof(Node.Children));