diff --git a/samples/RenderDemo/Pages/TransitionsPage.xaml b/samples/RenderDemo/Pages/TransitionsPage.xaml
index f9f69fb341..1985074b0f 100644
--- a/samples/RenderDemo/Pages/TransitionsPage.xaml
+++ b/samples/RenderDemo/Pages/TransitionsPage.xaml
@@ -141,6 +141,39 @@
       <Style Selector="Border.Shadow:pointerover">
         <Setter Property="BoxShadow" Value="inset 30 30 20 30 Green, 20 40 20 10 Red"/>
       </Style>
+
+      <Style Selector="Border.Rect10">
+        <Setter Property="Transitions">
+          <Transitions>
+            <BrushTransition Property="Background" Duration="0:0:0.5" />
+          </Transitions>
+        </Setter>
+        <Setter Property="Background" Value="Red" />
+      </Style>
+
+      <Style Selector="Border.Rect10:pointerover">
+        <Setter Property="Background" Value="Orange" />
+      </Style>
+
+      <Style Selector="Border.Rect11">
+        <Setter Property="Transitions">
+          <Transitions>
+            <BrushTransition Property="Background" Duration="0:0:0.5" />
+          </Transitions>
+        </Setter>
+        <Setter Property="Background" Value="Red" />
+      </Style>
+
+      <Style Selector="Border.Rect11:pointerover">
+        <Setter Property="Background" >
+          <LinearGradientBrush StartPoint="0%,0%" EndPoint="100%,100%">
+            <LinearGradientBrush.GradientStops>
+              <GradientStop Offset="0" Color="Red"/>
+              <GradientStop Offset="1" Color="Blue"/>
+            </LinearGradientBrush.GradientStops>
+          </LinearGradientBrush>
+        </Setter>
+      </Style>
     </Styles>
   </UserControl.Styles>
 
@@ -166,6 +199,9 @@
 
         <Border Classes="Test Shadow" CornerRadius="10" Child="{x:Null}" />
         <Border Classes="Test Shadow" CornerRadius="0 30 60 0" Child="{x:Null}" />
+
+        <Border Classes="Test Rect10" />
+        <Border Classes="Test Rect11" />
       </WrapPanel>
     </StackPanel>
   </Grid>
diff --git a/src/Avalonia.Controls/ExperimentalAcrylicBorder.cs b/src/Avalonia.Controls/ExperimentalAcrylicBorder.cs
index 0a01767a07..57861163d6 100644
--- a/src/Avalonia.Controls/ExperimentalAcrylicBorder.cs
+++ b/src/Avalonia.Controls/ExperimentalAcrylicBorder.cs
@@ -3,6 +3,7 @@ using Avalonia.Layout;
 using Avalonia.Media;
 using Avalonia.Platform;
 using System;
+using Avalonia.Media.Immutable;
 
 namespace Avalonia.Controls
 {
@@ -90,7 +91,7 @@ namespace Avalonia.Controls
             }
             else
             {
-                _borderRenderHelper.Render(context, Bounds.Size, new Thickness(), CornerRadius, new SolidColorBrush(Material.FallbackColor), null, default);
+                _borderRenderHelper.Render(context, Bounds.Size, new Thickness(), CornerRadius, new ImmutableSolidColorBrush(Material.FallbackColor), null, default);
             }
         }
 
diff --git a/src/Avalonia.Controls/Presenters/TextPresenter.cs b/src/Avalonia.Controls/Presenters/TextPresenter.cs
index 3bec46a9ac..ff63e5644f 100644
--- a/src/Avalonia.Controls/Presenters/TextPresenter.cs
+++ b/src/Avalonia.Controls/Presenters/TextPresenter.cs
@@ -6,6 +6,7 @@ using Avalonia.Metadata;
 using Avalonia.Threading;
 using Avalonia.VisualTree;
 using Avalonia.Layout;
+using Avalonia.Media.Immutable;
 
 namespace Avalonia.Controls.Presenters
 {
@@ -360,32 +361,31 @@ namespace Avalonia.Controls.Presenters
 
             RenderInternal(context);
 
-            if (selectionStart == selectionEnd)
+            if (selectionStart == selectionEnd && _caretBlink)
             {
-                var caretBrush = CaretBrush;
+                var caretBrush = CaretBrush?.ToImmutable();
 
                 if (caretBrush is null)
                 {
-                    var backgroundColor = (Background as SolidColorBrush)?.Color;
+                    var backgroundColor = (Background as ISolidColorBrush)?.Color;
                     if (backgroundColor.HasValue)
                     {
                         byte red = (byte)~(backgroundColor.Value.R);
                         byte green = (byte)~(backgroundColor.Value.G);
                         byte blue = (byte)~(backgroundColor.Value.B);
 
-                        caretBrush = new SolidColorBrush(Color.FromRgb(red, green, blue));
+                        caretBrush = new ImmutableSolidColorBrush(Color.FromRgb(red, green, blue));
                     }
                     else
+                    {
                         caretBrush = Brushes.Black;
+                    }
                 }
 
-                if (_caretBlink)
-                {
-                    var (p1, p2) = GetCaretPoints();
-                    context.DrawLine(
-                        new Pen(caretBrush, 1),
-                        p1, p2);
-                }
+                var (p1, p2) = GetCaretPoints();
+                context.DrawLine(
+                    new ImmutablePen(caretBrush, 1),
+                    p1, p2);
             }
         }
 
diff --git a/src/Avalonia.Controls/TickBar.cs b/src/Avalonia.Controls/TickBar.cs
index 6ea5277a55..237bc2ce1d 100644
--- a/src/Avalonia.Controls/TickBar.cs
+++ b/src/Avalonia.Controls/TickBar.cs
@@ -1,6 +1,7 @@
 using Avalonia.Collections;
 using Avalonia.Layout;
 using Avalonia.Media;
+using Avalonia.Media.Immutable;
 using Avalonia.Utilities;
 
 namespace Avalonia.Controls
@@ -295,7 +296,7 @@ namespace Avalonia.Controls
                 endPoint = pt;
             }
 
-            var pen = new Pen(Fill, 1.0d);
+            var pen = new ImmutablePen(Fill?.ToImmutable(), 1.0d);
 
             // Is it Vertical?
             if (Placement == TickBarPlacement.Left || Placement == TickBarPlacement.Right)
diff --git a/src/Avalonia.Controls/Utils/BorderRenderHelper.cs b/src/Avalonia.Controls/Utils/BorderRenderHelper.cs
index 3128753781..f8ab58d46e 100644
--- a/src/Avalonia.Controls/Utils/BorderRenderHelper.cs
+++ b/src/Avalonia.Controls/Utils/BorderRenderHelper.cs
@@ -1,5 +1,6 @@
 using System;
 using Avalonia.Media;
+using Avalonia.Media.Immutable;
 using Avalonia.Platform;
 using Avalonia.Utilities;
 
@@ -114,9 +115,9 @@ namespace Avalonia.Controls.Utils
                 var borderThickness = _borderThickness.Top;
                 IPen pen = null;
 
-                if (borderThickness > 0)
+                if (borderBrush != null && borderThickness > 0)
                 {
-                    pen = new Pen(borderBrush, borderThickness);
+                    pen = new ImmutablePen(borderBrush.ToImmutable(), borderThickness);
                 }
 
                 var rect = new Rect(_size);
diff --git a/src/Avalonia.Diagnostics/Diagnostics/ViewModels/AvaloniaPropertyViewModel.cs b/src/Avalonia.Diagnostics/Diagnostics/ViewModels/AvaloniaPropertyViewModel.cs
index 63f68501a7..e4c4ca6115 100644
--- a/src/Avalonia.Diagnostics/Diagnostics/ViewModels/AvaloniaPropertyViewModel.cs
+++ b/src/Avalonia.Diagnostics/Diagnostics/ViewModels/AvaloniaPropertyViewModel.cs
@@ -26,9 +26,11 @@ namespace Avalonia.Diagnostics.ViewModels
         public AvaloniaProperty Property { get; }
         public override object Key => Property;
         public override string Name { get; }
-        public bool IsAttached => Property.IsAttached;
+        public override bool? IsAttached => 
+            Property.IsAttached;
 
-        public string Priority => _priority;
+        public override string Priority =>
+            _priority;
 
         public override string Type => _type;
 
@@ -69,7 +71,7 @@ namespace Avalonia.Diagnostics.ViewModels
                 if (val != null)
                 {
                     RaiseAndSetIfChanged(ref _priority, val.Priority.ToString(), nameof(Priority));
-                    RaiseAndSetIfChanged(ref _group, IsAttached ? "Attached Properties" : "Properties", nameof(Group));
+                    RaiseAndSetIfChanged(ref _group, IsAttached == true ? "Attached Properties" : "Properties", nameof(Group));
                 }
                 else
                 {
diff --git a/src/Avalonia.Diagnostics/Diagnostics/ViewModels/ClrPropertyViewModel.cs b/src/Avalonia.Diagnostics/Diagnostics/ViewModels/ClrPropertyViewModel.cs
index 6b2dbb7bae..65626aeea5 100644
--- a/src/Avalonia.Diagnostics/Diagnostics/ViewModels/ClrPropertyViewModel.cs
+++ b/src/Avalonia.Diagnostics/Diagnostics/ViewModels/ClrPropertyViewModel.cs
@@ -49,6 +49,12 @@ namespace Avalonia.Diagnostics.ViewModels
             }
         }
 
+        public override string Priority => 
+            string.Empty;
+
+        public override bool? IsAttached => 
+            default;
+
         // [MemberNotNull(nameof(_type))]
         public override void Update()
         {
diff --git a/src/Avalonia.Diagnostics/Diagnostics/ViewModels/ControlDetailsViewModel.cs b/src/Avalonia.Diagnostics/Diagnostics/ViewModels/ControlDetailsViewModel.cs
index 1f7205eb16..3790951b0c 100644
--- a/src/Avalonia.Diagnostics/Diagnostics/ViewModels/ControlDetailsViewModel.cs
+++ b/src/Avalonia.Diagnostics/Diagnostics/ViewModels/ControlDetailsViewModel.cs
@@ -18,7 +18,7 @@ namespace Avalonia.Diagnostics.ViewModels
     {
         private readonly IVisual _control;
         private readonly IDictionary<object, List<PropertyViewModel>> _propertyIndex;
-        private AvaloniaPropertyViewModel? _selectedProperty;
+        private PropertyViewModel? _selectedProperty;
         private bool _snapshotStyles;
         private bool _showInactiveStyles;
         private string? _styleStatus;
@@ -139,7 +139,7 @@ namespace Avalonia.Diagnostics.ViewModels
 
         public ObservableCollection<PseudoClassViewModel> PseudoClasses { get; }
 
-        public AvaloniaPropertyViewModel? SelectedProperty
+        public PropertyViewModel? SelectedProperty
         {
             get => _selectedProperty;
             set => RaiseAndSetIfChanged(ref _selectedProperty, value);
diff --git a/src/Avalonia.Diagnostics/Diagnostics/ViewModels/PropertyViewModel.cs b/src/Avalonia.Diagnostics/Diagnostics/ViewModels/PropertyViewModel.cs
index bfd098985a..fdbd8c1aa3 100644
--- a/src/Avalonia.Diagnostics/Diagnostics/ViewModels/PropertyViewModel.cs
+++ b/src/Avalonia.Diagnostics/Diagnostics/ViewModels/PropertyViewModel.cs
@@ -16,7 +16,9 @@ namespace Avalonia.Diagnostics.ViewModels
         public abstract string Group { get; }
         public abstract string Type { get; }
         public abstract string Value { get; set; }
-        public abstract void Update();
+        public abstract string Priority { get; }
+        public abstract bool? IsAttached { get;  }
+        public abstract void Update();        
 
         protected static string ConvertToString(object? value)
         {
diff --git a/src/Avalonia.Visuals/Animation/Transitions/BrushTransition.cs b/src/Avalonia.Visuals/Animation/Transitions/BrushTransition.cs
new file mode 100644
index 0000000000..cc5af1b4b1
--- /dev/null
+++ b/src/Avalonia.Visuals/Animation/Transitions/BrushTransition.cs
@@ -0,0 +1,59 @@
+using System;
+using Avalonia.Animation.Animators;
+using Avalonia.Animation.Easings;
+using Avalonia.Media;
+
+#nullable enable
+
+namespace Avalonia.Animation
+{
+    /// <summary>
+    /// Transition class that handles <see cref="AvaloniaProperty"/> with <see cref="IBrush"/> type.
+    /// Only values of <see cref="ISolidColorBrush"/> will transition correctly at the moment.
+    /// </summary>
+    public class BrushTransition : Transition<IBrush?>
+    {
+        private static readonly ISolidColorBrushAnimator s_animator = new ISolidColorBrushAnimator();
+
+        public override IObservable<IBrush?> DoTransition(IObservable<double> progress, IBrush? oldValue, IBrush? newValue)
+        {
+            var oldSolidColorBrush = TryGetSolidColorBrush(oldValue);
+            var newSolidColorBrush = TryGetSolidColorBrush(newValue);
+
+            if (oldSolidColorBrush != null && newSolidColorBrush != null)
+            {
+                return new AnimatorTransitionObservable<ISolidColorBrush, ISolidColorBrushAnimator>(
+                    s_animator, progress, Easing, oldSolidColorBrush, newSolidColorBrush);
+            }
+
+            return new IncompatibleTransitionObservable(progress, Easing, oldValue, newValue);
+        }
+
+        private static ISolidColorBrush? TryGetSolidColorBrush(IBrush? brush)
+        {
+            if (brush is null)
+            {
+                return Brushes.Transparent;
+            }
+
+            return brush as ISolidColorBrush;
+        }
+
+        private class IncompatibleTransitionObservable : TransitionObservableBase<IBrush?>
+        {
+            private readonly IBrush? _from;
+            private readonly IBrush? _to;
+
+            public IncompatibleTransitionObservable(IObservable<double> progress, Easing easing, IBrush? from, IBrush? to) : base(progress, easing)
+            {
+                _from = from;
+                _to = to;
+            }
+
+            protected override IBrush? ProduceValue(double progress)
+            {
+                return progress < 0.5 ? _from : _to;
+            }
+        }
+    }
+}
diff --git a/src/Avalonia.Visuals/Media/Immutable/ImmutablePen.cs b/src/Avalonia.Visuals/Media/Immutable/ImmutablePen.cs
index 32624fbf45..3256f4b11a 100644
--- a/src/Avalonia.Visuals/Media/Immutable/ImmutablePen.cs
+++ b/src/Avalonia.Visuals/Media/Immutable/ImmutablePen.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 
 namespace Avalonia.Media.Immutable
 {
@@ -44,6 +45,8 @@ namespace Avalonia.Media.Immutable
             PenLineJoin lineJoin = PenLineJoin.Miter,
             double miterLimit = 10.0)
         {
+            Debug.Assert(!(brush is IMutableBrush));
+
             Brush = brush;
             Thickness = thickness;
             LineCap = lineCap;
diff --git a/tests/Avalonia.Visuals.UnitTests/Media/PenTests.cs b/tests/Avalonia.Visuals.UnitTests/Media/PenTests.cs
index c2a1a5f9e4..8c25019606 100644
--- a/tests/Avalonia.Visuals.UnitTests/Media/PenTests.cs
+++ b/tests/Avalonia.Visuals.UnitTests/Media/PenTests.cs
@@ -59,9 +59,9 @@ namespace Avalonia.Visuals.UnitTests.Media
         }
 
         [Fact]
-        public void Equality_Is_Implemented_Between_Immutable_And_Mmutable_Pens()
+        public void Equality_Is_Implemented_Between_Immutable_And_Mutable_Pens()
         {
-            var brush = new SolidColorBrush(Colors.Red);
+            var brush = new ImmutableSolidColorBrush(Colors.Red);
             var target1 = new ImmutablePen(
                 brush: brush,
                 thickness: 2,
@@ -83,7 +83,7 @@ namespace Avalonia.Visuals.UnitTests.Media
         [Fact]
         public void Equality_Is_Implemented_Between_Mutable_And_Immutable_DashStyles()
         {
-            var brush = new SolidColorBrush(Colors.Red);
+            var brush = new ImmutableSolidColorBrush(Colors.Red);
             var target1 = new ImmutablePen(
                 brush: brush,
                 thickness: 2,