Minor fixes.

samples/ControlCatalog/SideBar.xaml

@@ -1,4 +1,5 @@
-<Styles xmlns="https://github.com/avaloniaui" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+<Styles xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
   <Style Selector="TabControl.sidebar">
     <Setter Property="Template">
       <ControlTemplate>
@@ -32,9 +33,20 @@
     <Setter Property="FontSize" Value="14"/>
     <Setter Property="Margin" Value="0"/>
     <Setter Property="Padding" Value="16"/>
+    <Setter Property="Opacity" Value="0.5"/>
+    <Setter Property="Transitions">
+      <Transitions>
+        <DoubleTransition Property="Opacity" Duration="0:0:0.5"/>
+      </Transitions>
+    </Setter>
+  </Style>
+
+  <Style Selector="TabControl.sidebar TabStripItem:pointerover">
+    <Setter Property="Opacity" Value="1"/>
   </Style>
 
   <Style Selector="TabControl.sidebar TabStripItem:selected">
     <Setter Property="Background" Value="{DynamicResource ThemeAccentBrush2}"/>
+    <Setter Property="Opacity" Value="1"/>
   </Style>
 </Styles>

samples/RenderTest/MainWindow.xaml

@@ -1,6 +1,6 @@
 <Window xmlns="https://github.com/avaloniaui"
         Title="Avalonia Render Test"
-        xmlns:pages="clr-namespace:RenderTest.Pages;assembly=RenderTest" MinWidth="400" MinHeight="200"
+        xmlns:pages="clr-namespace:RenderTest.Pages;assembly=RenderTest" MinWidth="900" MinHeight="600"
         >
   <DockPanel>
     <Menu DockPanel.Dock="Top">

samples/RenderTest/Pages/AnimationsPage.xaml

@@ -1,7 +1,6 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <Grid>
-    <Grid.Styles>
-      <Styles>
+  <UserControl.Styles>
+        <Styles>
         <Style Selector="Rectangle.Test">
           <Setter Property="Margin" Value="15"/>
           <Setter Property="Width" Value="100"/>
@@ -55,7 +54,8 @@
           </Style.Animations>
         </Style>
       </Styles>
-    </Grid.Styles>
+  </UserControl.Styles>
+  <Grid> 
     <StackPanel VerticalAlignment="Center" 
                 HorizontalAlignment="Center"
                 ClipToBounds="False">

src/Avalonia.Styling/Styling/Style.cs

@@ -8,6 +8,7 @@ using System.Reactive.Linq;
 using Avalonia.Controls;
 using Avalonia.Metadata;
 using Avalonia.Animation;
+using System.Diagnostics;
 
 namespace Avalonia.Styling
 {
@@ -117,7 +118,18 @@ namespace Avalonia.Styling
 
                     foreach (var animation in Animations)
                     {
-                        subs.Add(animation.Apply((Animatable)control, match.ObservableResult));
+                        // TODO: Needs more work in passing the appropriate
+                        //       observable.
+                        IObservable<bool> obsMatch = match.ObservableResult;
+
+                        if (match.ImmediateResult == true)
+                        {
+                            obsMatch = Observable.Return(true);
+                        } 
+
+                        var sub = animation.Apply((Animatable)control, obsMatch);
+                        subs.Add(sub);
+
                     }
 
                     foreach (var setter in Setters)

src/Avalonia.Visuals/Animation/Keyframes/TransformKeyFrames.cs

@@ -16,7 +16,7 @@ namespace Avalonia.Animation.Keyframes
     public class TransformKeyFrames : KeyFrames<double>
     {
         DoubleKeyFrames childKeyFrames;
-        
+
         /// <inheritdoc/>
         public override IDisposable Apply(Animation animation, Animatable control, IObservable<bool> obsMatch)
         {
@@ -27,45 +27,52 @@ namespace Avalonia.Animation.Keyframes
             {
                 var renderTransformType = ctrl.RenderTransform.GetType();
 
+                if (childKeyFrames == null)
+                {
+                    InitializeInternalDoubleKeyFrames();
+                }
+
                 // It's only 1 transform object so let's target that.
                 if (renderTransformType == Property.OwnerType)
                 {
-                    var targetTransform = Convert.ChangeType(ctrl.RenderTransform, Property.OwnerType);
-
-                    if (childKeyFrames == null)
-                    {
-                        childKeyFrames = new DoubleKeyFrames();
-
-                        foreach (KeyFrame k in this)
-                        {
-                            childKeyFrames.Add(k);
-                        }
-
-                        childKeyFrames.Property = Property;
-                    }
-
                     return childKeyFrames.Apply(animation, ctrl.RenderTransform, obsMatch);
                 }
+                // TODO: Selection within TransformGroup is not working
                 if (renderTransformType == typeof(TransformGroup))
                 {
-                    foreach (Transform t in ((TransformGroup)ctrl.RenderTransform).Children)
+                    foreach (Transform transform in ((TransformGroup)ctrl.RenderTransform).Children)
                     {
-                        if (renderTransformType == Property.OwnerType)
+                        if (transform.GetType() == Property.OwnerType)
                         {
-
+                             return childKeyFrames.Apply(animation, transform, obsMatch);
                         }
                     }
+                }
+
+                return null;
+
+                // // Throw exception when there is no appropriate transform object found.
+                // throw new Exception
+                //     ($"TransformKeyFrame hasn't found an appropriate Transform object with type {Property.OwnerType} in target {control}.");
 
-                    // not existing in the transform
 
-                }
             }
             else
             {
-                throw new InvalidProgramException($"Unsupported property {Property}");
+                throw new Exception($"Unsupported property {Property}");
+            }
+        }
+
+        void InitializeInternalDoubleKeyFrames()
+        {
+            childKeyFrames = new DoubleKeyFrames();
+
+            foreach (KeyFrame keyframe in this)
+            {
+                childKeyFrames.Add(keyframe);
             }
 
-            return null;
+            childKeyFrames.Property = Property;
         }
 
         /// <inheritdocs/>