diff --git a/.travis.yml b/.travis.yml
index d80d24f32c..b0c0c807cb 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,6 +11,8 @@ mono:
   - 5.2.0
 dotnet: 2.1.200
 script:
+  - sudo apt-get update
+  - sudo apt-get install castxml
   - ./build.sh --target "Travis" --configuration "Release"
 notifications:
   email: false
diff --git a/build.cake b/build.cake
index e5a4e3470d..d7efa69399 100644
--- a/build.cake
+++ b/build.cake
@@ -2,9 +2,10 @@
 // ADDINS
 ///////////////////////////////////////////////////////////////////////////////
 
-#tool "nuget:?package=NuGet.CommandLine&version=4.3.0"
-#tool "nuget:?package=JetBrains.ReSharper.CommandLineTools&version=2017.1.20170613.162720"
-
+#addin "nuget:?package=NuGet.Core&version=2.14.0"
+#tool "nuget:?package=NuGet.CommandLine&version=4.7.1"
+#tool "nuget:?package=JetBrains.ReSharper.CommandLineTools&version=2018.2.3"
+  
 ///////////////////////////////////////////////////////////////////////////////
 // TOOLS
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/src/Avalonia.ReactiveUI/ReactiveUserControl.cs b/src/Avalonia.ReactiveUI/ReactiveUserControl.cs
new file mode 100644
index 0000000000..04c6f100a6
--- /dev/null
+++ b/src/Avalonia.ReactiveUI/ReactiveUserControl.cs
@@ -0,0 +1,44 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using Avalonia;
+using Avalonia.VisualTree;
+using Avalonia.Controls;
+using ReactiveUI;
+
+namespace Avalonia
+{
+    /// <summary>
+    /// A ReactiveUI UserControl that implements <see cref="IViewFor{TViewModel}"/> 
+    /// and will activate your ViewModel automatically if it supports activation.
+    /// </summary>
+    /// <typeparam name="TViewModel">ViewModel type.</typeparam>
+    public class ReactiveUserControl<TViewModel> : UserControl, IViewFor<TViewModel> where TViewModel : class
+    {
+        public static readonly AvaloniaProperty<TViewModel> ViewModelProperty = AvaloniaProperty
+            .Register<ReactiveWindow<TViewModel>, TViewModel>(nameof(ViewModel));
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ReactiveUserControl{TViewModel}"/> class.
+        /// </summary>
+        public ReactiveUserControl()
+        {
+            DataContextChanged += (sender, args) => ViewModel = DataContext as TViewModel;
+        }
+
+        /// <summary>
+        /// The ViewModel.
+        /// </summary>
+        public TViewModel ViewModel
+        {
+            get => GetValue(ViewModelProperty);
+            set => SetValue(ViewModelProperty, value);
+        }
+
+        object IViewFor.ViewModel
+        {
+            get => ViewModel;
+            set => ViewModel = (TViewModel)value;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/Avalonia.ReactiveUI/ReactiveWindow.cs b/src/Avalonia.ReactiveUI/ReactiveWindow.cs
new file mode 100644
index 0000000000..bb50a37764
--- /dev/null
+++ b/src/Avalonia.ReactiveUI/ReactiveWindow.cs
@@ -0,0 +1,44 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using Avalonia;
+using Avalonia.VisualTree;
+using Avalonia.Controls;
+using ReactiveUI;
+
+namespace Avalonia 
+{
+    /// <summary>
+    /// A ReactiveUI Window that implements <see cref="IViewFor{TViewModel}"/>
+    /// and will activate your ViewModel automatically if it supports activation.
+    /// </summary>
+    /// <typeparam name="TViewModel">ViewModel type.</typeparam>
+    public class ReactiveWindow<TViewModel> : Window, IViewFor<TViewModel> where TViewModel : class
+    {
+        public static readonly AvaloniaProperty<TViewModel> ViewModelProperty = AvaloniaProperty
+            .Register<ReactiveWindow<TViewModel>, TViewModel>(nameof(ViewModel));
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ReactiveWindow{TViewModel}"/> class.
+        /// </summary>
+        public ReactiveWindow()
+        {
+            DataContextChanged += (sender, args) => ViewModel = DataContext as TViewModel;
+        }
+            
+        /// <summary>
+        /// The ViewModel.
+        /// </summary>
+        public TViewModel ViewModel
+        {
+            get => GetValue(ViewModelProperty);
+            set => SetValue(ViewModelProperty, value);
+        }
+
+        object IViewFor.ViewModel
+        {
+            get => ViewModel;
+            set => ViewModel = (TViewModel)value;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/Gtk/Avalonia.Gtk3/Gtk3Platform.cs b/src/Gtk/Avalonia.Gtk3/Gtk3Platform.cs
index 9604e9975b..8444e509fd 100644
--- a/src/Gtk/Avalonia.Gtk3/Gtk3Platform.cs
+++ b/src/Gtk/Avalonia.Gtk3/Gtk3Platform.cs
@@ -66,7 +66,7 @@ namespace Avalonia.Gtk3
                 DisplayClassName =
                     Utf8Buffer.StringFromPtr(Native.GTypeName(Marshal.ReadIntPtr(Marshal.ReadIntPtr(disp))));
 
-                using (var utf = new Utf8Buffer("avalonia.app." + Guid.NewGuid()))
+                using (var utf = new Utf8Buffer($"avalonia.app.a{Guid.NewGuid().ToString("N")}"))
                     App = Native.GtkApplicationNew(utf, 0);
                 //Mark current thread as UI thread
                 s_tlsMarker = true;
diff --git a/src/Markup/Avalonia.Markup/Data/MultiBinding.cs b/src/Markup/Avalonia.Markup/Data/MultiBinding.cs
index 4c47ef32e0..4921b7c9d7 100644
--- a/src/Markup/Avalonia.Markup/Data/MultiBinding.cs
+++ b/src/Markup/Avalonia.Markup/Data/MultiBinding.cs
@@ -61,7 +61,7 @@ namespace Avalonia.Data
 
             var targetType = targetProperty?.PropertyType ?? typeof(object);
             var children = Bindings.Select(x => x.Initiate(target, null));
-            var input = children.Select(x => x.Subject).CombineLatest().Select(x => ConvertValue(x, targetType));
+            var input = children.Select(x => x.Observable).CombineLatest().Select(x => ConvertValue(x, targetType));
             var mode = Mode == BindingMode.Default ?
                 targetProperty?.GetMetadata(target.GetType()).DefaultBindingMode : Mode;
 
diff --git a/tests/Avalonia.Markup.UnitTests/Data/MultiBindingTests.cs b/tests/Avalonia.Markup.UnitTests/Data/MultiBindingTests.cs
index fb23a38cce..78c538d99d 100644
--- a/tests/Avalonia.Markup.UnitTests/Data/MultiBindingTests.cs
+++ b/tests/Avalonia.Markup.UnitTests/Data/MultiBindingTests.cs
@@ -41,6 +41,37 @@ namespace Avalonia.Markup.UnitTests.Data
             Assert.Equal("1,2,3", result);
         }
 
+        [Fact]
+        public async Task Nested_MultiBinding_Should_Be_Set_Up()
+        {
+            var source = new { A = 1, B = 2, C = 3 };
+            var binding = new MultiBinding
+            {
+                Converter = new ConcatConverter(),
+                Bindings =
+                {
+                    new Binding { Path = "A" },
+                    new MultiBinding
+                    {
+                        Converter = new ConcatConverter(),
+                        Bindings =
+                        {
+                            new Binding { Path = "B"},
+                            new Binding { Path = "C"}
+                        }
+                    }
+                }
+            };
+
+            var target = new Mock<IAvaloniaObject>().As<IControl>();
+            target.Setup(x => x.GetValue(Control.DataContextProperty)).Returns(source);
+
+            var observable = binding.Initiate(target.Object, null).Observable;
+            var result = await observable.Take(1);
+
+            Assert.Equal("1,2,3", result);
+        }
+
         [Fact]
         public void Should_Return_FallbackValue_When_Converter_Returns_UnsetValue()
         {
diff --git a/tests/Avalonia.ReactiveUI.UnitTests/AvaloniaActivationForViewFetcherTest.cs b/tests/Avalonia.ReactiveUI.UnitTests/AvaloniaActivationForViewFetcherTest.cs
index bda55276a8..b782311729 100644
--- a/tests/Avalonia.ReactiveUI.UnitTests/AvaloniaActivationForViewFetcherTest.cs
+++ b/tests/Avalonia.ReactiveUI.UnitTests/AvaloniaActivationForViewFetcherTest.cs
@@ -23,7 +23,8 @@ namespace Avalonia
 
             public TestUserControlWithWhenActivated()
             {
-                this.WhenActivated(disposables => {
+                this.WhenActivated(disposables => 
+                {
                     Active = true;
                     Disposable
                         .Create(() => Active = false)
@@ -38,7 +39,8 @@ namespace Avalonia
 
             public TestWindowWithWhenActivated()
             {
-                this.WhenActivated(disposables => {
+                this.WhenActivated(disposables => 
+                {
                     Active = true;
                     Disposable
                         .Create(() => Active = false)
@@ -47,6 +49,42 @@ namespace Avalonia
             }
         }
 
+        public class ActivatableViewModel : ISupportsActivation
+        {
+            public ViewModelActivator Activator { get; }
+
+            public bool IsActivated { get; private set; }
+
+            public ActivatableViewModel() 
+            {
+                Activator = new ViewModelActivator();
+                this.WhenActivated(disposables => 
+                {
+                    IsActivated = true;
+                    Disposable
+                        .Create(() => IsActivated = false)
+                        .DisposeWith(disposables);
+                });
+            }
+        }
+
+        public class ActivatableWindow : ReactiveWindow<ActivatableViewModel>
+        {
+            public ActivatableWindow() => this.WhenActivated(disposables => { });
+        }
+
+        public class ActivatableUserControl : ReactiveUserControl<ActivatableViewModel>
+        {
+            public ActivatableUserControl() => this.WhenActivated(disposables => { });
+        }
+
+        public AvaloniaActivationForViewFetcherTest()
+        {
+            Locator.CurrentMutable.RegisterConstant(
+                new AvaloniaActivationForViewFetcher(), 
+                typeof(IActivationForViewFetcher));
+        }
+
         [Fact]
         public void Visual_Element_Is_Activated_And_Deactivated()
         {
@@ -86,10 +124,6 @@ namespace Avalonia
         [Fact]
         public void Activation_For_View_Fetcher_Should_Support_When_Activated()
         {
-            Locator.CurrentMutable.RegisterConstant(
-                new AvaloniaActivationForViewFetcher(), 
-                typeof(IActivationForViewFetcher));
-
             var userControl = new TestUserControlWithWhenActivated();
             Assert.False(userControl.Active);
 
@@ -104,10 +138,6 @@ namespace Avalonia
         [Fact]
         public void Activation_For_View_Fetcher_Should_Support_Windows() 
         {
-            Locator.CurrentMutable.RegisterConstant(
-                new AvaloniaActivationForViewFetcher(), 
-                typeof(IActivationForViewFetcher));
-
             using (var application = UnitTestApplication.Start(TestServices.MockWindowingPlatform)) 
             {
                 var window = new TestWindowWithWhenActivated();
@@ -120,5 +150,37 @@ namespace Avalonia
                 Assert.False(window.Active);
             }
         }
+
+        [Fact]
+        public void Activatable_Window_View_Model_Is_Activated_And_Deactivated() 
+        {
+            using (var application = UnitTestApplication.Start(TestServices.MockWindowingPlatform)) 
+            {
+                var viewModel = new ActivatableViewModel();
+                var window = new ActivatableWindow { ViewModel = viewModel };
+                Assert.False(viewModel.IsActivated);
+
+                window.Show();
+                Assert.True(viewModel.IsActivated);
+
+                window.Close();
+                Assert.False(viewModel.IsActivated);
+            }
+        }
+
+        [Fact]
+        public void Activatable_User_Control_View_Model_Is_Activated_And_Deactivated() 
+        {
+            var root = new TestRoot();
+            var viewModel = new ActivatableViewModel();
+            var control = new ActivatableUserControl { ViewModel = viewModel };
+            Assert.False(viewModel.IsActivated);
+
+            root.Child = control;
+            Assert.True(viewModel.IsActivated);
+
+            root.Child = null;
+            Assert.False(viewModel.IsActivated);
+        }
     }
 }
\ No newline at end of file
diff --git a/tools/packages.config b/tools/packages.config
index 3c65df896f..05018882e8 100644
--- a/tools/packages.config
+++ b/tools/packages.config
@@ -1,4 +1,4 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-    <package id="Cake" version="0.28.0" />
+    <package id="Cake" version="0.30.0" />
 </packages>