diff --git a/Microsoft.Toolkit.Uwp.UI.Controls.Layout/GridSplitter/GridSplitter.xaml b/Microsoft.Toolkit.Uwp.UI.Controls.Layout/GridSplitter/GridSplitter.xaml
index 2b98ce6be8d..451e054d16f 100644
--- a/Microsoft.Toolkit.Uwp.UI.Controls.Layout/GridSplitter/GridSplitter.xaml
+++ b/Microsoft.Toolkit.Uwp.UI.Controls.Layout/GridSplitter/GridSplitter.xaml
@@ -4,29 +4,37 @@
 
     <ResourceDictionary.ThemeDictionaries>
         <ResourceDictionary x:Key="Default">
-            <SolidColorBrush x:Key="SystemControlSplitterPointerOver" Color="{ThemeResource SystemBaseLowColor}" />
-            <SolidColorBrush x:Key="SystemControlSplitterPressed" Color="{ThemeResource SystemBaseHighColor}" />
+            <SolidColorBrush x:Key="SystemControlSplitterPointerOver"
+                             Color="{ThemeResource SystemBaseLowColor}" />
+            <SolidColorBrush x:Key="SystemControlSplitterPressed"
+                             Color="{ThemeResource SystemBaseHighColor}" />
         </ResourceDictionary>
         <ResourceDictionary x:Key="HighContrast">
-            <SolidColorBrush x:Key="SystemControlSplitterPointerOver" Color="{ThemeResource SystemColorHighlightColor}" />
-            <SolidColorBrush x:Key="SystemControlSplitterPressed" Color="{ThemeResource SystemColorHighlightColor}" />
+            <SolidColorBrush x:Key="SystemControlSplitterPointerOver"
+                             Color="{ThemeResource SystemColorHighlightColor}" />
+            <SolidColorBrush x:Key="SystemControlSplitterPressed"
+                             Color="{ThemeResource SystemColorHighlightColor}" />
         </ResourceDictionary>
     </ResourceDictionary.ThemeDictionaries>
 
     <Style TargetType="local:GridSplitter">
-        <Setter Property="IsTabStop" Value="True"></Setter>
-        <Setter Property="UseSystemFocusVisuals" Value="True"></Setter>
-        <Setter Property="HorizontalAlignment" Value="Stretch"></Setter>
-        <Setter Property="VerticalAlignment" Value="Stretch"></Setter>
-        <Setter Property="IsFocusEngagementEnabled" Value="True"></Setter>
-        <Setter Property="MinWidth" Value="16"></Setter>
-        <Setter Property="MinHeight" Value="16"></Setter>
-        <Setter Property="Background" Value="{ThemeResource SystemControlHighlightChromeHighBrush}"></Setter>
+        <Setter Property="IsTabStop" Value="True" />
+        <Setter Property="UseSystemFocusVisuals" Value="True" />
+        <Setter Property="HorizontalAlignment" Value="Stretch" />
+        <Setter Property="VerticalAlignment" Value="Stretch" />
+        <Setter Property="IsFocusEngagementEnabled" Value="True" />
+        <Setter Property="MinWidth" Value="16" />
+        <Setter Property="MinHeight" Value="16" />
+        <Setter Property="Background" Value="{ThemeResource SystemControlHighlightChromeHighBrush}" />
         <Setter Property="GripperForeground" Value="{ThemeResource SystemControlForegroundAltHighBrush}" />
         <Setter Property="Template">
             <Setter.Value>
                 <ControlTemplate TargetType="local:GridSplitter">
-                    <Grid x:Name="RootGrid" Background="{TemplateBinding Background}">
+                    <Grid x:Name="RootGrid"
+                          Background="{TemplateBinding Background}">
+                        <ContentPresenter HorizontalContentAlignment="Stretch"
+                                          VerticalContentAlignment="Stretch"
+                                          Content="{TemplateBinding Element}" />
                         <VisualStateManager.VisualStateGroups>
                             <VisualStateGroup x:Name="GridSplitterStates">
                                 <VisualState x:Name="Normal" />
@@ -42,7 +50,6 @@
                                 </VisualState>
                             </VisualStateGroup>
                         </VisualStateManager.VisualStateGroups>
-                        <ContentPresenter Content="{TemplateBinding Element}" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" />
                     </Grid>
                 </ControlTemplate>
             </Setter.Value>
diff --git a/UITests/UITests.App/App.AppService.xaml.cs b/UITests/UITests.App/App.AppService.xaml.cs
index b10b7621082..ced08c8935f 100644
--- a/UITests/UITests.App/App.AppService.xaml.cs
+++ b/UITests/UITests.App/App.AppService.xaml.cs
@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using Microsoft.Toolkit.Mvvm.Messaging;
 using UITests.App.Pages;
@@ -49,6 +50,8 @@ private async void OnAppServiceRequestReceived(AppServiceConnection sender, AppS
                 return;
             }
 
+            Log.Comment("Received Command: {0}", cmd);
+
             switch (cmd)
             {
                 case "OpenPage":
@@ -65,6 +68,44 @@ private async void OnAppServiceRequestReceived(AppServiceConnection sender, AppS
 
                     await args.Request.SendResponseAsync(pageResponse ? OkResult : BadResult);
 
+                    break;
+                case "Custom":
+                    if (!TryGetValueAndLog(message, "Id", out var id) || !_customCommands.ContainsKey(id))
+                    {
+                        await args.Request.SendResponseAsync(BadResult);
+                        break;
+                    }
+
+                    Log.Comment("Received request for custom command: {0}", id);
+
+                    try
+                    {
+                        ValueSet response = await _customCommands[id].Invoke(message);
+
+                        if (response != null)
+                        {
+                            response.Add("Status", "OK");
+                        }
+                        else
+                        {
+                            await args.Request.SendResponseAsync(BadResult);
+                            break;
+                        }
+
+                        await args.Request.SendResponseAsync(response);
+                    }
+                    catch (Exception e)
+                    {
+                        ValueSet errmsg = new() { { "Status", "BAD" }, { "Exception", e.Message }, { "StackTrace", e.StackTrace } };
+                        if (e.InnerException != null)
+                        {
+                            errmsg.Add("InnerException", e.InnerException.Message);
+                            errmsg.Add("InnerExceptionStackTrace", e.InnerException.StackTrace);
+                        }
+
+                        await args.Request.SendResponseAsync(errmsg);
+                    }
+
                     break;
                 default:
                     break;
@@ -77,11 +118,15 @@ private async void OnAppServiceRequestReceived(AppServiceConnection sender, AppS
 
         private void OnAppServicesCanceled(IBackgroundTaskInstance sender, BackgroundTaskCancellationReason reason)
         {
+            Log.Error("Background Task Instance Canceled. Reason: {0}", reason.ToString());
+
             _appServiceDeferral.Complete();
         }
 
         private void AppServiceConnection_ServiceClosed(AppServiceConnection sender, AppServiceClosedEventArgs args)
         {
+            Log.Error("AppServiceConnection Service Closed. AppServicesClosedStatus: {0}", args.Status.ToString());
+
             _appServiceDeferral.Complete();
         }
 
@@ -118,5 +163,12 @@ private static bool TryGetValueAndLog(ValueSet message, string key, out string v
 
             return true;
         }
+
+        private Dictionary<string, Func<ValueSet, Task<ValueSet>>> _customCommands = new();
+
+        internal void RegisterCustomCommand(string id, Func<ValueSet, Task<ValueSet>> customCommandFunction)
+        {
+            _customCommands.Add(id, customCommandFunction);
+        }
     }
-}
\ No newline at end of file
+}
diff --git a/UITests/UITests.App/App.xaml.cs b/UITests/UITests.App/App.xaml.cs
index ce3a59d2bf8..118d20ccc3a 100644
--- a/UITests/UITests.App/App.xaml.cs
+++ b/UITests/UITests.App/App.xaml.cs
@@ -6,9 +6,11 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
+using UITests.App.Commands;
 using UITests.App.Pages;
 using Windows.ApplicationModel;
 using Windows.ApplicationModel.Activation;
+using Windows.System;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
 using Windows.UI.Xaml.Navigation;
diff --git a/UITests/UITests.App/Commands/VisualTreeHelperCommands.cs b/UITests/UITests.App/Commands/VisualTreeHelperCommands.cs
new file mode 100644
index 00000000000..432596b14e7
--- /dev/null
+++ b/UITests/UITests.App/Commands/VisualTreeHelperCommands.cs
@@ -0,0 +1,105 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Linq;
+using System.Reflection;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using System.Threading.Tasks;
+using Microsoft.Toolkit;
+using Microsoft.Toolkit.Uwp;
+using Microsoft.Toolkit.Uwp.UI;
+using UITests.App.Pages;
+using Windows.Foundation.Collections;
+using Windows.System;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+
+namespace UITests.App.Commands
+{
+    public static class VisualTreeHelperCommands
+    {
+        private static DispatcherQueue Queue { get; set; }
+
+        private static JsonSerializerOptions SerializerOptions { get; } = new JsonSerializerOptions(JsonSerializerDefaults.General)
+        {
+            NumberHandling = JsonNumberHandling.AllowNamedFloatingPointLiterals,
+        };
+
+        public static void Initialize(DispatcherQueue uiThread)
+        {
+            Queue = uiThread;
+
+            (App.Current as App).RegisterCustomCommand("VisualTreeHelper.FindElementProperty", FindElementProperty);
+        }
+
+        public static async Task<ValueSet> FindElementProperty(ValueSet arguments)
+        {
+            ValueSet results = new ValueSet();
+
+            if (Queue == null)
+            {
+                Log.Error("VisualTreeHelper - Missing UI DispatcherQueue");
+                return null;
+            }
+
+            await Queue.EnqueueAsync(() =>
+            {
+                // Dispatch?
+                var content = Window.Current.Content as Frame;
+
+                if (content == null)
+                {
+                    Log.Error("VisualTreeHelper.FindElementProperty - Window has no content.");
+                    return;
+                }
+
+                if (arguments.TryGetValue("ElementName", out object value) && value is string name &&
+                    arguments.TryGetValue("Property", out object value2) && value2 is string propertyName)
+                {
+                    Log.Comment("VisualTreeHelper.FindElementProperty('{0}', '{1}')", name, propertyName);
+
+                    // 1. Find Element in Visual Tree
+                    var element = content.FindDescendant(name);
+
+                    try
+                    {
+                        Log.Comment("VisualTreeHelper.FindElementProperty - Found Element? {0}", element != null);
+
+                        var typeinfo = element.GetType().GetTypeInfo();
+
+                        Log.Comment("Element Type: {0}", typeinfo.FullName);
+
+                        var prop = element.GetType().GetTypeInfo().GetProperty(propertyName);
+
+                        if (prop == null)
+                        {
+                            Log.Error("VisualTreeHelper.FindElementProperty - Couldn't find Property named {0} on type {1}", propertyName, typeinfo.FullName);
+                            return;
+                        }
+
+                        // 2. Get the property using reflection
+                        var propValue = prop.GetValue(element);
+
+                        // 3. Serialize and return the result
+                        results.Add("Result", JsonSerializer.Serialize(propValue, SerializerOptions));
+                    }
+                    catch (Exception e)
+                    {
+                        Log.Error("Error {0}", e.Message);
+                        Log.Error("StackTrace:\n{0}", e.StackTrace);
+                    }
+                }
+            });
+
+            if (results.Count > 0)
+            {
+                return results;
+            }
+
+            return null; // Failure
+        }
+    }
+}
diff --git a/UITests/UITests.App/MainTestHost.xaml.cs b/UITests/UITests.App/MainTestHost.xaml.cs
index ff48cad4c52..3ef439aaac6 100644
--- a/UITests/UITests.App/MainTestHost.xaml.cs
+++ b/UITests/UITests.App/MainTestHost.xaml.cs
@@ -7,6 +7,7 @@
 using System.Threading.Tasks;
 using Microsoft.Toolkit.Mvvm.Messaging;
 using Microsoft.Toolkit.Uwp;
+using UITests.App.Commands;
 using UITests.App.Pages;
 using Windows.System;
 using Windows.UI.Xaml;
@@ -33,6 +34,9 @@ public MainTestHost()
             WeakReferenceMessenger.Default.Register<RequestPageMessage>(this);
 
             _queue = DispatcherQueue.GetForCurrentThread();
+
+            // Initialize Custom Commands for AppService
+            VisualTreeHelperCommands.Initialize(_queue);
         }
 
         public void Receive(RequestPageMessage message)
diff --git a/UITests/UITests.App/Package.appxmanifest b/UITests/UITests.App/Package.appxmanifest
index 5e031837706..bb5c6d4e96e 100644
--- a/UITests/UITests.App/Package.appxmanifest
+++ b/UITests/UITests.App/Package.appxmanifest
@@ -2,7 +2,8 @@
   xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10"
   xmlns:mp="http://schemas.microsoft.com/appx/2014/phone/manifest"
   xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10"
-  IgnorableNamespaces="uap mp">
+  xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
+  IgnorableNamespaces="uap mp rescap">
 
   <Identity
     Name="3568ebdf-5b6b-4ddd-bb17-462d614ba50f"
@@ -48,5 +49,7 @@
 
   <Capabilities>
     <Capability Name="internetClient" />
+    <!-- Our AppService Background Connection will Timeout after a period of time otherwise. -->
+    <rescap:Capability Name="extendedBackgroundTaskTime"/>
   </Capabilities>
 </Package>
\ No newline at end of file
diff --git a/UITests/UITests.App/Properties/Default.rd.xml b/UITests/UITests.App/Properties/Default.rd.xml
index dc591a4ce9c..84833a6bf2f 100644
--- a/UITests/UITests.App/Properties/Default.rd.xml
+++ b/UITests/UITests.App/Properties/Default.rd.xml
@@ -21,6 +21,8 @@
       the application package. The asterisks are not wildcards.
     -->
     <Assembly Name="*Application*" Dynamic="Required All" />
+    <Namespace Name="Windows.UI.Xaml.Controls" Dynamic="Required All" />
+    <Namespace Name="Microsoft.UI.Xaml.Controls" Dynamic="Required All" />
     <!-- Add your application specific runtime directives here. -->
   </Application>
 </Directives>
\ No newline at end of file
diff --git a/UITests/UITests.App/TestInterop.cs b/UITests/UITests.App/TestInterop.cs
index 956f34f9e35..f17e12142c7 100644
--- a/UITests/UITests.App/TestInterop.cs
+++ b/UITests/UITests.App/TestInterop.cs
@@ -2,7 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
+using System.Diagnostics;
 using Windows.UI.Xaml;
 
 namespace UITests.App.Pages
@@ -37,9 +37,13 @@ private static void LogMessage(string level, string format, object[] args)
                 format = format.Replace("{", "{{").Replace("}", "}}");
             }
 
+            var message = string.Format(format, args);
+
+            Debug.WriteLine(message);
+
             // Send back to Test Harness via AppService
             // TODO: Make this a cleaner connection/pattern
-            ((App)Application.Current).SendLogMessage(level, string.Format(format, args));
+            _ = ((App)Application.Current).SendLogMessage(level, message);
         }
     }
 }
\ No newline at end of file
diff --git a/UITests/UITests.App/UITests.App.csproj b/UITests/UITests.App/UITests.App.csproj
index e9d4feb937d..21515c4f9b8 100644
--- a/UITests/UITests.App/UITests.App.csproj
+++ b/UITests/UITests.App/UITests.App.csproj
@@ -132,6 +132,7 @@
     <Compile Include="App.AppService.xaml.cs">
       <DependentUpon>App.xaml</DependentUpon>
     </Compile>
+    <Compile Include="Commands\VisualTreeHelperCommands.cs" />
     <Compile Include="HomePage.xaml.cs">
       <DependentUpon>HomePage.xaml</DependentUpon>
     </Compile>
@@ -178,6 +179,9 @@
     <PackageReference Include="MUXAppTestHelpers">
       <Version>0.0.4</Version>
     </PackageReference>
+    <PackageReference Include="System.Text.Json">
+      <Version>5.0.2</Version>
+    </PackageReference>
   </ItemGroup>
   <ItemGroup>
     <None Include="UITests.App.pfx" />
diff --git a/UITests/UITests.Tests.MSTest/UITests.Tests.MSTest.csproj b/UITests/UITests.Tests.MSTest/UITests.Tests.MSTest.csproj
index f69d5fc4da4..c1133a0ad15 100644
--- a/UITests/UITests.Tests.MSTest/UITests.Tests.MSTest.csproj
+++ b/UITests/UITests.Tests.MSTest/UITests.Tests.MSTest.csproj
@@ -30,6 +30,7 @@
     <PackageReference Include="System.Reflection.TypeExtensions" Version="4.5.1" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.7.1" />
     <PackageReference Include="Microsoft.Windows.Apps.Test" Version="1.0.181205002" />
+    <PackageReference Include="System.Text.Json" Version="5.0.2" />
   </ItemGroup>
 
   <Import Project="..\UITests.Tests.Shared\UITests.Tests.Shared.projitems" Label="Shared" />
diff --git a/UITests/UITests.Tests.Shared/Controls/GridSplitterTest.cs b/UITests/UITests.Tests.Shared/Controls/GridSplitterTest.cs
new file mode 100644
index 00000000000..2827b4f0b8e
--- /dev/null
+++ b/UITests/UITests.Tests.Shared/Controls/GridSplitterTest.cs
@@ -0,0 +1,225 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Microsoft.Windows.Apps.Test.Foundation;
+using Microsoft.Windows.Apps.Test.Foundation.Controls;
+using Windows.UI.Xaml.Tests.MUXControls.InteractionTests.Common;
+using Windows.UI.Xaml.Tests.MUXControls.InteractionTests.Infra;
+using System.Linq;
+using System.Threading.Tasks;
+using System.Collections.Generic;
+using System.Dynamic;
+using System;
+
+#if USING_TAEF
+using WEX.Logging.Interop;
+using WEX.TestExecution;
+using WEX.TestExecution.Markup;
+#else
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+#endif
+
+namespace UITests.Tests
+{
+
+    [TestClass]
+    public class GridSplitterTest : UITestBase
+    {
+        [ClassInitialize]
+        [TestProperty("RunAs", "User")]
+        [TestProperty("Classification", "ScenarioTestSuite")]
+        [TestProperty("Platform", "Any")]
+        public static void ClassInitialize(TestContext testContext)
+        {
+            TestEnvironment.Initialize(testContext, WinUICsUWPSampleApp);
+        }
+
+        [TestMethod]
+        [TestPage("GridSplitterTestPage")]
+        public async Task TestGridSplitterDragHorizontalAsync()
+        {
+            var amount = 50;
+            var tolerance = 10;
+
+            var grid = FindElement.ByName("GridSplitterRoot");
+            var gridSplitter = FindElement.ById("GridSplitterHorizontal");
+            var box = FindElement.ByName("TopLeftBox");
+
+            Verify.IsNotNull(grid, "Can't find GridSplitterRoot");
+            Verify.IsNotNull(gridSplitter, "Can't find Horizontal GridSplitter");
+            Verify.IsNotNull(box, "Can't find box");
+
+            var width = box.BoundingRectangle.Width;
+
+            ColumnDefinition columnDefinitionStart = (await VisualTreeHelper.FindElementPropertyAsync<List<ColumnDefinition>>("GridSplitterRoot", "ColumnDefinitions"))?.FirstOrDefault();
+
+            Verify.IsNotNull(columnDefinitionStart, "Couldn't retrieve Column Definition");
+
+            // Drag to the Left
+            InputHelper.DragDistance(gridSplitter, amount, Direction.West, 1000);
+
+            Wait.ForMilliseconds(1050);
+            Wait.ForIdle();
+
+            ColumnDefinition columnDefinitionEnd = (await VisualTreeHelper.FindElementPropertyAsync<List<ColumnDefinition>>("GridSplitterRoot", "ColumnDefinitions"))?.FirstOrDefault();
+
+            Wait.ForIdle();
+
+            Verify.IsTrue(Math.Abs(columnDefinitionStart.ActualWidth - amount - columnDefinitionEnd.ActualWidth) <= tolerance, $"ColumnDefinition not in range expected {columnDefinitionStart.ActualWidth - amount} was {columnDefinitionEnd.ActualWidth}");
+
+            Verify.IsTrue(Math.Abs(width - amount - box.BoundingRectangle.Width) <= tolerance, $"Bounding box not in range expected {width - amount} was {box.BoundingRectangle.Width}.");
+        }
+
+        [TestMethod]
+        [TestPage("GridSplitterTestPage")]
+        public async Task TestGridSplitterDragHorizontalPastMinimumAsync()
+        {
+            var amount = 150;
+
+            var gridSplitter = FindElement.ById("GridSplitterHorizontal");
+
+            Verify.IsNotNull(gridSplitter, "Can't find Horizontal GridSplitter");
+
+            // Drag to the Left
+            InputHelper.DragDistance(gridSplitter, amount, Direction.West, 1000);
+
+            Wait.ForMilliseconds(1050);
+            Wait.ForIdle();
+
+            ColumnDefinition columnDefinitionEnd = (await VisualTreeHelper.FindElementPropertyAsync<List<ColumnDefinition>>("GridSplitterRoot", "ColumnDefinitions"))?.FirstOrDefault();
+
+            Wait.ForIdle();
+
+            Verify.AreEqual(columnDefinitionEnd.MinWidth, columnDefinitionEnd.ActualWidth, "Column was not the minimum size expected.");
+        }
+
+        [TestMethod]
+        [TestPage("GridSplitterTestPage")]
+        public async Task TestGridSplitterDragHorizontalPastMaximumAsync()
+        {
+            var amount = 150;
+
+            var gridSplitter = FindElement.ById("GridSplitterHorizontal");
+
+            Verify.IsNotNull(gridSplitter, "Can't find Horizontal GridSplitter");
+
+            // Drag to the Left
+            InputHelper.DragDistance(gridSplitter, amount, Direction.East, 1000);
+
+            Wait.ForMilliseconds(1050);
+            Wait.ForIdle();
+
+            ColumnDefinition columnDefinitionEnd = (await VisualTreeHelper.FindElementPropertyAsync<List<ColumnDefinition>>("GridSplitterRoot", "ColumnDefinitions"))?.FirstOrDefault();
+
+            Wait.ForIdle();
+
+            Verify.AreEqual(columnDefinitionEnd.MaxWidth, columnDefinitionEnd.ActualWidth, "Column was not the maximum size expected.");
+        }
+
+        [TestMethod]
+        [TestPage("GridSplitterTestPage")]
+        public async Task TestGridSplitterDragVerticalAsync()
+        {
+            var amount = 50;
+            var tolerance = 10;
+
+            var grid = FindElement.ByName("GridSplitterRoot");
+            var gridSplitter = FindElement.ById("GridSplitterVertical");
+
+            Verify.IsNotNull(grid, "Can't find GridSplitterRoot");
+            Verify.IsNotNull(gridSplitter, "Can't find Vertical GridSplitter");
+
+            RowDefinition rowDefinitionStart = (await VisualTreeHelper.FindElementPropertyAsync<List<RowDefinition>>("GridSplitterRoot", "RowDefinitions"))?.FirstOrDefault();
+
+            Verify.IsNotNull(rowDefinitionStart, "Couldn't retrieve Row Definition");
+
+            // Drag to the Left
+            InputHelper.DragDistance(gridSplitter, amount, Direction.North, 1000);
+
+            Wait.ForMilliseconds(1050);
+            Wait.ForIdle();
+
+            RowDefinition rowDefinitionEnd = (await VisualTreeHelper.FindElementPropertyAsync<List<RowDefinition>>("GridSplitterRoot", "RowDefinitions"))?.FirstOrDefault();
+
+            Wait.ForIdle();
+
+            Verify.IsTrue(Math.Abs(rowDefinitionStart.ActualHeight - amount - rowDefinitionEnd.ActualHeight) <= tolerance, $"RowDefinition not in range expected {rowDefinitionStart.ActualHeight - amount} was {rowDefinitionEnd.ActualHeight}");
+        }
+
+        [TestMethod]
+        [TestPage("GridSplitterTestPage")]
+        public async Task TestGridSplitterDragVerticalPastMinimumAsync()
+        {
+            var amount = 150;
+
+            var gridSplitter = FindElement.ById("GridSplitterVertical");
+
+            Verify.IsNotNull(gridSplitter, "Can't find Vertical GridSplitter");
+
+            // Drag to the Left
+            InputHelper.DragDistance(gridSplitter, amount, Direction.North, 1000);
+
+            Wait.ForMilliseconds(1050);
+            Wait.ForIdle();
+
+            RowDefinition rowDefinitionEnd = (await VisualTreeHelper.FindElementPropertyAsync<List<RowDefinition>>("GridSplitterRoot", "RowDefinitions"))?.FirstOrDefault();
+
+            Wait.ForIdle();
+
+            Verify.AreEqual(rowDefinitionEnd.MinHeight, rowDefinitionEnd.ActualHeight, "Row was not the minimum size expected.");
+        }
+
+        [TestMethod]
+        [TestPage("GridSplitterTestPage")]
+        public async Task TestGridSplitterDragVerticalPastMaximumAsync()
+        {
+            var amount = 150;
+
+            var gridSplitter = FindElement.ById("GridSplitterVertical");
+
+            Verify.IsNotNull(gridSplitter, "Can't find Vertical GridSplitter");
+
+            // Drag to the Left
+            InputHelper.DragDistance(gridSplitter, amount, Direction.South, 1000);
+
+            Wait.ForMilliseconds(1050);
+            Wait.ForIdle();
+
+            RowDefinition rowDefinitionEnd = (await VisualTreeHelper.FindElementPropertyAsync<List<RowDefinition>>("GridSplitterRoot", "RowDefinitions"))?.FirstOrDefault();
+
+            Wait.ForIdle();
+
+            Verify.AreEqual(rowDefinitionEnd.MaxHeight, rowDefinitionEnd.ActualHeight, "Row was not the maximum size expected.");
+        }
+
+        private class ColumnDefinition
+        {
+            public GridLength Width { get; set; }
+
+            public double ActualWidth { get; set; }
+
+            public double MinWidth { get; set; }
+
+            public double MaxWidth { get; set; }
+        }
+
+        private class RowDefinition
+        {
+            public GridLength Height { get; set; }
+
+            public double ActualHeight { get; set; }
+
+            public double MinHeight { get; set; }
+
+            public double MaxHeight { get; set; }
+        }
+
+        private class GridLength
+        {
+            public int GridUnitType { get; set; } // 0 Auto, 1 Pixel, 2 Star
+
+            public double Value { get; set; }
+        }
+    }
+}
diff --git a/UITests/UITests.Tests.Shared/Controls/GridSplitterTestPage.xaml b/UITests/UITests.Tests.Shared/Controls/GridSplitterTestPage.xaml
new file mode 100644
index 00000000000..074df833eb2
--- /dev/null
+++ b/UITests/UITests.Tests.Shared/Controls/GridSplitterTestPage.xaml
@@ -0,0 +1,94 @@
+<Page x:Class="UITests.App.Pages.GridSplitterTestPage"
+      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+      xmlns:controls="using:Microsoft.Toolkit.Uwp.UI.Controls"
+      xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+      xmlns:sys="using:System"
+      Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"
+      mc:Ignorable="d">
+
+    <Page.Resources>
+        <Style TargetType="Border">
+            <Setter Property="BorderThickness" Value="1,1,0,0" />
+            <Setter Property="Padding" Value="16" />
+            <Setter Property="BorderBrush" Value="{ThemeResource SystemControlHighlightChromeHighBrush}" />
+        </Style>
+
+        <Style TargetType="TextBlock">
+            <Setter Property="TextWrapping" Value="Wrap" />
+        </Style>
+    </Page.Resources>
+
+    <!--  Grid isn't normally an element that's findable so we need to use AutomationProperties.Name  -->
+    <Grid x:Name="GridSplitterRoot"
+          Height="500"
+          Margin="48"
+          VerticalAlignment="Top"
+          AutomationProperties.Name="GridSplitterRoot"
+          BorderBrush="{ThemeResource SystemControlHighlightChromeHighBrush}"
+          BorderThickness="0,0,1,1">
+        <Grid.RowDefinitions>
+            <RowDefinition Height="200"
+                           MinHeight="100"
+                           MaxHeight="300" />
+            <RowDefinition />
+        </Grid.RowDefinitions>
+        <Grid.ColumnDefinitions>
+            <ColumnDefinition Width="200"
+                              MinWidth="100"
+                              MaxWidth="300" />
+            <ColumnDefinition />
+            <ColumnDefinition />
+        </Grid.ColumnDefinitions>
+
+        <Border Grid.Row="0"
+                Grid.Column="0"
+                AutomationProperties.Name="TopLeftBox">
+            <TextBlock Text="This text to simulate the resizing feature of the Grid Splitter Control, try to move the splitter to see the effect RowDefinition MinHeight='100'" />
+        </Border>
+        <Border Grid.Row="0"
+                Grid.Column="1">
+            <TextBlock Text="This text to simulate the resizing feature of the Grid Splitter Control, try to move the splitter to see the effect" />
+        </Border>
+        <Border Grid.Row="0"
+                Grid.Column="2">
+            <TextBlock Text="This text to simulate the resizing feature of the Grid Splitter Control, try to move the splitter to see the effect" />
+        </Border>
+
+        <Border Grid.Row="1"
+                Grid.Column="0">
+            <TextBlock Text="This text to simulate the resizing feature of the Grid Splitter Control, try to move the splitter to see the effect" />
+        </Border>
+        <Border Grid.Row="1"
+                Grid.Column="1">
+            <TextBlock Text="This text to simulate the resizing feature of the Grid Splitter Control, try to move the splitter to see the effect" />
+        </Border>
+        <Border Grid.Row="1"
+                Grid.Column="2">
+            <TextBlock Text="This text to simulate the resizing feature of the Grid Splitter Control, try to move the splitter to see the effect" />
+        </Border>
+
+        <!--  Column Grid Splitter  -->
+        <controls:GridSplitter x:Name="GridSplitterHorizontal"
+                               Grid.Column="1"
+                               Width="16"
+                               HorizontalAlignment="Left"/>
+
+        <!--  Row Grid Splitter  -->
+        <controls:GridSplitter x:Name="GridSplitterVertical"
+                               Grid.Row="1"
+                               Grid.ColumnSpan="3"
+                               Height="16"
+                               VerticalAlignment="Top">
+            <controls:GridSplitter.Element>
+                <TextBlock HorizontalAlignment="Center"
+                           VerticalAlignment="Center"
+                           FontFamily="Segoe MDL2 Assets"
+                           Foreground="White"
+                           IsHitTestVisible="False"
+                           Text="&#xE76F;" />
+            </controls:GridSplitter.Element>
+        </controls:GridSplitter>
+    </Grid>
+</Page>
diff --git a/UITests/UITests.Tests.Shared/Controls/GridSplitterTestPage.xaml.cs b/UITests/UITests.Tests.Shared/Controls/GridSplitterTestPage.xaml.cs
new file mode 100644
index 00000000000..39c39b82dfd
--- /dev/null
+++ b/UITests/UITests.Tests.Shared/Controls/GridSplitterTestPage.xaml.cs
@@ -0,0 +1,20 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+
+namespace UITests.App.Pages
+{
+    /// <summary>
+    /// An empty page that can be used on its own or navigated to within a Frame.
+    /// </summary>
+    public sealed partial class GridSplitterTestPage : Page
+    {
+        public GridSplitterTestPage()
+        {
+            this.InitializeComponent();
+        }
+    }
+}
diff --git a/UITests/UITests.Tests.Shared/TestAssembly.cs b/UITests/UITests.Tests.Shared/TestAssembly.cs
index 1992c2b94e1..47d45afbcdd 100644
--- a/UITests/UITests.Tests.Shared/TestAssembly.cs
+++ b/UITests/UITests.Tests.Shared/TestAssembly.cs
@@ -44,6 +44,7 @@ private static async Task InitalizeComService()
             CommunicationService = new AppServiceConnection();
 
             CommunicationService.RequestReceived += CommunicationService_RequestReceived;
+            CommunicationService.ServiceClosed += CommunicationService_ServiceClosed;
 
             // Here, we use the app service name defined in the app service
             // provider's Package.appxmanifest file in the <Extension> section.
@@ -63,6 +64,11 @@ private static async Task InitalizeComService()
             }
         }
 
+        private static void CommunicationService_ServiceClosed(AppServiceConnection sender, AppServiceClosedEventArgs args)
+        {
+            Log.Warning("[Harness] Communication Service Closed! AppServiceClosedStatus: {0}", args.Status.ToString());
+        }
+
         internal static Task<bool> OpenPage(string pageName)
         {
             Log.Comment("[Harness] Sending Host Page Request: {0}", pageName);
@@ -74,6 +80,16 @@ internal static Task<bool> OpenPage(string pageName)
             });
         }
 
+        internal static async Task<AppServiceResponse> SendCustomMessageToApp(ValueSet message)
+        {
+            if (CommunicationService is null)
+            {
+                await InitalizeComService();
+            }
+
+            return await CommunicationService.SendMessageAsync(message);
+        }
+
         private static async Task<bool> SendMessageToApp(ValueSet message)
         {
             if (CommunicationService is null)
@@ -83,10 +99,20 @@ private static async Task<bool> SendMessageToApp(ValueSet message)
 
             var response = await CommunicationService.SendMessageAsync(message);
 
+            return CheckResponseStatusOK(response);
+        }
+
+        internal static bool CheckResponseStatusOK(AppServiceResponse response)
+        {
+            object message = null;
+            var hasMessage = response?.Message?.TryGetValue("Status", out message) is true;
+
+            Log.Comment("[Harness] Checking Response AppServiceResponseStatus({0}), Message Status: {1}", response.Status.ToString(), message?.ToString());
+
             return response.Status == AppServiceResponseStatus.Success
-                && response.Message.TryGetValue("Status", out var s)
-                && s is string status
-                && status == "OK";
+                    && hasMessage
+                    && message is string status
+                    && status == "OK";
         }
 
         private static void CommunicationService_RequestReceived(AppServiceConnection sender, AppServiceRequestReceivedEventArgs args)
diff --git a/UITests/UITests.Tests.Shared/UITests.Tests.Shared.projitems b/UITests/UITests.Tests.Shared/UITests.Tests.Shared.projitems
index 192c7eb36a2..136a1a627ca 100644
--- a/UITests/UITests.Tests.Shared/UITests.Tests.Shared.projitems
+++ b/UITests/UITests.Tests.Shared/UITests.Tests.Shared.projitems
@@ -1,4 +1,4 @@
-<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <MSBuildAllProjects>$(MSBuildAllProjects);$(MSBuildThisFileFullPath)</MSBuildAllProjects>
     <HasSharedItems>true</HasSharedItems>
@@ -7,20 +7,19 @@
   <PropertyGroup Label="Configuration">
     <Import_RootNamespace>UITests.Tests.Shared</Import_RootNamespace>
   </PropertyGroup>
-
   <Choose>
     <!-- When we're in the test harness include all '*Test.cs' files -->
     <When Condition="'$(IsTestHarness)' == 'true'">
       <ItemGroup>
-        <Compile Include="$(MSBuildThisFileDirectory)**\*Test.cs" Exclude="**\bin\**\*Test.cs;**\obj\**\*Test.cs"/>
+        <Compile Include="$(MSBuildThisFileDirectory)**\*Test.cs" Exclude="**\bin\**\*Test.cs;**\obj\**\*Test.cs" />
         <!-- Base test helpers -->
         <Compile Include="$(MSBuildThisFileDirectory)UITestBase.cs" />
         <Compile Include="$(MSBuildThisFileDirectory)TestAssembly.cs" />
         <Compile Include="$(MSBuildThisFileDirectory)TestPageAttribute.cs" />
+        <Compile Include="$(MSBuildThisFileDirectory)VisualTreeHelper.cs" />
       </ItemGroup>
     </When>
   </Choose>
-
   <Choose>
     <!-- When we're in the UI app used by the test harness, include all the pages -->
     <When Condition="'$(IsTestHost)' == 'true'">
@@ -30,15 +29,15 @@
       </ItemGroup>
     </When>
   </Choose>
-
   <!-- Have a None Include as well to make all items visible in VS in the Shared Project -->
   <ItemGroup>
-    <None Include="$(MSBuildThisFileDirectory)**\*Test.cs" Exclude="**\bin\**\*Test.cs;**\obj\**\*Test.cs"/>
+    <None Include="$(MSBuildThisFileDirectory)**\*Test.cs" Exclude="**\bin\**\*Test.cs;**\obj\**\*Test.cs" />
     <None Include="$(MSBuildThisFileDirectory)**\*Page.xaml" Exclude="**\bin\**\*Page.xaml;**\obj\**\*Page.xaml" SubType="Designer" Generator="MSBuild:Compile" />
     <None Include="$(MSBuildThisFileDirectory)**\*Page.xaml.cs" DependentUpon="%(Filename)" />
     <!-- Base test helpers -->
     <None Include="$(MSBuildThisFileDirectory)UITestBase.cs" />
     <None Include="$(MSBuildThisFileDirectory)TestAssembly.cs" />
     <None Include="$(MSBuildThisFileDirectory)TestPageAttribute.cs" />
+    <None Include="$(MSBuildThisFileDirectory)VisualTreeHelper.cs" />
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/UITests/UITests.Tests.Shared/VisualTreeHelper.cs b/UITests/UITests.Tests.Shared/VisualTreeHelper.cs
new file mode 100644
index 00000000000..f558d12dfbb
--- /dev/null
+++ b/UITests/UITests.Tests.Shared/VisualTreeHelper.cs
@@ -0,0 +1,67 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using System.Threading.Tasks;
+
+#if USING_TAEF
+using WEX.Logging.Interop;
+#endif
+
+namespace UITests.Tests
+{
+    /// <summary>
+    /// Helper class to access some VisualTree info through our communication pipeline to the host app
+    /// using TestAssembly.SendMessageToApp.
+    /// </summary>
+    internal static class VisualTreeHelper
+    {
+        private static JsonSerializerOptions SerializerOptions { get; } = new JsonSerializerOptions(JsonSerializerDefaults.General)
+        {
+            NumberHandling = JsonNumberHandling.AllowNamedFloatingPointLiterals,
+        };
+
+        /// <summary>
+        /// Looks for the specified element by name and retrieves the specified property path.
+        /// </summary>
+        /// <param name="name">Name of element to search for.</param>
+        /// <param name="property">Name of property to retrieve from element.</param>
+        /// <typeparam name="T">Type of data to serialize result back as.</typeparam>
+        /// <returns>Retrieved value or default.</returns>
+        public static async Task<T> FindElementPropertyAsync<T>(string name, string property)
+        {
+            var response = await TestAssembly.SendCustomMessageToApp(new()
+            {
+                { "Command", "Custom" },
+                { "Id", "VisualTreeHelper.FindElementProperty" },
+                { "ElementName", name },
+                { "Property", property },
+            });
+
+            if (!TestAssembly.CheckResponseStatusOK(response))
+            {
+                Log.Error("[Harness] VisualTreeHelper: Error trying to retrieve property {0} from element named {1}.", property, name);
+
+                return default(T);
+            }
+
+            if (response.Message.TryGetValue("Result", out object value) && value is string str)
+            {
+                Log.Comment("[Harness] VisualTreeHelper.FindElementPropertyAsync - Received: {0}", str);
+
+                try
+                {
+                    return JsonSerializer.Deserialize<T>(str, SerializerOptions);
+                }
+                catch
+                {
+                    Log.Error("[Harness] VisualTreeHelper.FindElementPropertyAsync - Couldn't deserialize result as {0}", typeof(T));
+                }
+            }
+
+            return default(T);
+        }
+    }
+}
diff --git a/UITests/UITests.Tests.TAEF/UITests.Tests.TAEF.csproj b/UITests/UITests.Tests.TAEF/UITests.Tests.TAEF.csproj
index da8d60bfd20..18dc3731d9a 100644
--- a/UITests/UITests.Tests.TAEF/UITests.Tests.TAEF.csproj
+++ b/UITests/UITests.Tests.TAEF/UITests.Tests.TAEF.csproj
@@ -44,6 +44,8 @@
                       Version="10.0.19041.0" />
 
     <PackageReference Include="MUXTestInfra.TAEF" Version="0.0.4" />
+
+    <PackageReference Include="System.Text.Json" Version="5.0.2" />
     <PackageReference Include="TAEF.Redist.Wlk" Version="10.31.180822002" GeneratePathProperty="true" />
     <PackageReference Include="MUXCustomBuildTasks" Version="1.0.67" GeneratePathProperty="true" />
   </ItemGroup>
@@ -52,7 +54,7 @@
     <None Include="$(MSBuildThisFileDirectory)\..\UITests.App\AppPackages\*\*.msix" Link="%(Filename)%(Extension)" CopyToOutputDirectory="PreserveNewest" />
     <None Include="$(MSBuildThisFileDirectory)\..\UITests.App\AppPackages\*\Dependencies\$(PlatformTarget)\*.appx" Link="%(Filename)%(Extension)" CopyToOutputDirectory="PreserveNewest" />
     <None Include="$(MSBuildThisFileDirectory)\..\UITests.App\*.pfx" Link="%(Filename)%(Extension)" CopyToOutputDirectory="PreserveNewest" />
-    <None Include="$(PkgMUXCustomBuildTasks)\tools\x86\WttLog.dll"  CopyToOutputDirectory="PreserveNewest" />
+    <None Include="$(PkgMUXCustomBuildTasks)\tools\x86\WttLog.dll" CopyToOutputDirectory="PreserveNewest" />
   </ItemGroup>
 
   <ItemGroup>