[Visual|Logical]Tree extensions revamp (#3685)

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## Closes #3487 
<!-- Add the relevant issue number after the "#" mentioned above (for ex: Fixes #1234) which will automatically close the issue once the PR is merged. -->

<!-- Add a brief overview here of the feature/bug & fix. -->

## PR Type
What kind of change does this PR introduce?
<!-- Please uncomment one or more that apply to this PR. -->

 - Feature 
<!-- - Code style update (formatting) -->
<!-- - Refactoring (no functional changes, no api changes) -->
<!-- - Build or CI related changes -->
<!-- - Documentation content changes -->
<!-- - Sample app changes -->
<!-- - Other... Please describe: -->


## Overview
<!-- Please describe the current behavior that you are modifying, or link to a relevant issue. -->
There are some inconsistencies in the visual tree extensions mentioned in the linked issue, and some missing features.
This PR applies the changes mentioned in #3487 (comment).

## APIs breakdown

<details>
    <summary><b>VisualTree (click to expand):</b></summary>
<br/>

```csharp
namespace Microsoft.Toolkit.Uwp.UI.Extensions
{
    public static class VisualTree
    {
        static FrameworkElement? FindDescendant(this DependencyObject element, string name, StringComparison comparisonType = StringComparison.Ordinal);
        static T? FindDescendant<T>(this DependencyObject element) where T : notnull, DependencyObject;
        static DependencyObject? FindDescendant(this DependencyObject element, Type type);
        static T? FindDescendant<T>(this DependencyObject element, Func<T, bool> predicate) where T : notnull, DependencyObject;
        static T? FindDescendant<T, TState>(this DependencyObject element, TState state, Func<T, TState, bool> predicate) where T : notnull, DependencyObject;
        static FrameworkElement? FindDescendantOrSelf(this DependencyObject element, string name, StringComparison comparisonType = StringComparison.Ordinal);
        static T? FindDescendantOrSelf<T>(this DependencyObject element) where T : notnull, DependencyObject;
        static DependencyObject? FindDescendantOrSelf(this DependencyObject element, Type type);
        static T? FindDescendantOrSelf<T>(this DependencyObject element, Func<T, bool> predicate) where T : notnull, DependencyObject;
        static T? FindDescendantOrSelf<T, TState>(this DependencyObject element, TState state, Func<T, TState, bool> predicate) where T : notnull, DependencyObject;

        static IEnumerable<DependencyObject> FindDescendants(this DependencyObject element);

        static FrameworkElement? FindAscendant(this DependencyObject element, string name, StringComparison comparisonType = StringComparison.Ordinal);
        static T? FindAscendant<T>(this DependencyObject element) where T : notnull, DependencyObject;
        static DependencyObject? FindAscendant(this DependencyObject element, Type type);
        static T? FindAscendant<T>(this DependencyObject element, Func<T, bool> predicate) where T : notnull, DependencyObject;
        static T? FindAscendant<T, TState>(this DependencyObject element, TState state, Func<T, TState, bool> predicate) where T : notnull, DependencyObject;
        static FrameworkElement? FindAscendantOrSelf(this DependencyObject element, string name, StringComparison comparisonType = StringComparison.Ordinal);
        static T? FindAscendantOrSelf<T>(this DependencyObject element) where T : notnull, DependencyObject;
        static DependencyObject? FindAscendantOrSelf(this DependencyObject element, Type type);
        static T? FindAscendantOrSelf<T>(this DependencyObject element, Func<T, bool> predicate) where T : notnull, DependencyObject;
        static T? FindAscendantOrSelf<T, TState>(this DependencyObject element, TState state, Func<T, TState, bool> predicate) where T : notnull, DependencyObject;

        static IEnumerable<DependencyObject> FindAscendants(this DependencyObject element);
    }
}
```
</details>

<details>
    <summary><b>LogicalTree (click to expand):</b></summary>
<br/>

```csharp
namespace Microsoft.Toolkit.Uwp.UI.Extensions
{
    public static class LogicalTree
    {
        static FrameworkElement? FindChild(this FrameworkElement element, string name, StringComparison comparisonType = StringComparison.Ordinal);
        static T? FindChild<T>(this FrameworkElement element) where T : notnull, FrameworkElement;
        static FrameworkElement? FindChild(this FrameworkElement element, Type type);
        static T? FindChild<T>(this FrameworkElement element, Func<T, bool> predicate) where T : notnull, FrameworkElement;
        static T? FindChild<T, TState>(this FrameworkElement element, TState state, Func<T, TState, bool> predicate) where T : notnull, FrameworkElement;
        static FrameworkElement? FindChildOrSelf(this FrameworkElement element, string name, StringComparison comparisonType = StringComparison.Ordinal);
        static T? FindChildOrSelf<T>(this FrameworkElement element) where T : notnull, FrameworkElement;
        static FrameworkElement? FindChildOrSelf(this FrameworkElement element, Type type);
        static T? FindChildOrSelf<T>(this FrameworkElement element, Func<T, bool> predicate) where T : notnull, FrameworkElement;
        static T? FindChildOrSelf<T, TState>(this FrameworkElement element, TState state, Func<T, TState, bool> predicate) where T : notnull, FrameworkElement;

        static IEnumerable<FrameworkElement> FindChildren(this FrameworkElement element);

        static FrameworkElement? FindParent(this FrameworkElement element, string name, StringComparison comparisonType = StringComparison.Ordinal);
        static T? FindParent<T>(this FrameworkElement element) where T : notnull, FrameworkElement;
        static FrameworkElement? FindParent(this FrameworkElement element, Type type);
        static T? FindParent<T>(this FrameworkElement element, Func<T, bool> predicate) where T : notnull, FrameworkElement;
        static T? FindParent<T, TState>(this FrameworkElement element, TState state, Func<T, TState, bool> predicate) where T : notnull, FrameworkElement;
        static FrameworkElement? FindParentOrSelf(this FrameworkElement element, string name, StringComparison comparisonType = StringComparison.Ordinal);
        static T? FindParentOrSelf<T>(this FrameworkElement element) where T : notnull, FrameworkElement;
        static FrameworkElement? FindParentOrSelf(this FrameworkElement element, Type type);
        static T? FindParentOrSelf<T>(this FrameworkElement element, Func<T, bool> predicate) where T : notnull, FrameworkElement;
        static T? FindParentOrSelf<T, TState>(this FrameworkElement element, TState state, Func<T, TState, bool> predicate) where T : notnull, FrameworkElement;

        static IEnumerable<FrameworkElement> FindParents(this FrameworkElement element);
        
        static UIElement? TryGetContentControl(this FrameworkElement element);
        static object? TryFindResource(this FrameworkElement element, object resourceKey);
    }
}
```
</details>

## PR Checklist

Please check if your PR fulfills the following requirements:

- [ ] Tested code with current [supported SDKs](../readme.md#supported)
- [ ] Pull Request has been submitted to the documentation repository [instructions](..\contributing.md#docs). Link: <!-- docs PR link -->
- [ ] Sample in sample app has been added / updated (for bug fixes / features)
    - [ ] Icon has been created (if new sample) following the [Thumbnail Style Guide and templates](https://github.com/windows-toolkit/WindowsCommunityToolkit-design-assets)
- [ ] New major technical changes in the toolkit have or will be added to the [Wiki](https://github.com/windows-toolkit/WindowsCommunityToolkit/wiki) e.g. build changes, source generators, testing infrastructure, sample creation changes, etc...
- [ ] Tests for the changes have been added (for bug fixes / features) (if applicable)
- [X] Header has been added to all new source files (run *build/UpdateHeaders.bat*)
- [ ] Contains **NO** breaking changes

<!-- If this PR contains a breaking change, please describe the impact and migration path for existing applications below. 
     Please note that breaking changes are likely to be rejected within minor release cycles or held until major versions. -->


## Other information
Opening as draft, missing updated/revamped unit tests.

Microsoft.Toolkit.Uwp.SampleApp/Pages/SampleController.xaml.cs

@@ -517,7 +517,7 @@ private void UpdateXamlRender(string text)
 
                 if (CurrentSample.HasType)
                 {
-                    root = SamplePage?.FindDescendantByName("XamlRoot");
+                    root = SamplePage?.FindDescendant("XamlRoot");
 
                     if (root is Panel)
                     {

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/AdaptiveGridView/AdaptiveGridViewPage.xaml.cs

@@ -27,7 +27,7 @@ public AdaptiveGridViewPage()
 
         public async void OnXamlRendered(FrameworkElement control)
         {
-            _adaptiveGridViewControl = control.FindDescendantByName("AdaptiveGridViewControl") as AdaptiveGridView;
+            _adaptiveGridViewControl = control.FindDescendant("AdaptiveGridViewControl") as AdaptiveGridView;
             if (_adaptiveGridViewControl != null)
             {
                 var allPhotos = await new Data.PhotosDataSource().GetItemsAsync();

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/BladeView/BladePage.xaml.cs

@@ -25,8 +25,8 @@ public BladePage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            bladeView = control.FindChildByName("BladeView") as BladeView;
-            addBlade = control.FindChildByName("AddBlade") as Button;
+            bladeView = control.FindChild("BladeView") as BladeView;
+            addBlade = control.FindChild("AddBlade") as Button;
 
             if (addBlade != null)
             {

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/CameraPreview/CameraPreviewPage.xaml.cs

@@ -54,14 +54,14 @@ public async void OnXamlRendered(FrameworkElement control)
                 _cameraPreviewControl.CameraHelper.FrameArrived += CameraPreviewControl_FrameArrived;
             }
 
-            _imageControl = control.FindDescendantByName("CurrentFrameImage") as Image;
+            _imageControl = control.FindDescendant("CurrentFrameImage") as Image;
             if (_imageControl != null)
             {
                 _softwareBitmapSource = new SoftwareBitmapSource();
                 _imageControl.Source = _softwareBitmapSource;
             }
 
-            _errorMessageText = control.FindDescendantByName("ErrorMessage") as TextBlock;
+            _errorMessageText = control.FindDescendant("ErrorMessage") as TextBlock;
 
             semaphoreSlim.Release();
         }

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/Carousel/CarouselPage.xaml.cs

@@ -29,7 +29,7 @@ public CarouselPage()
 
         public async void OnXamlRendered(FrameworkElement control)
         {
-            carouselControl = control.FindDescendantByName("CarouselControl") as Carousel;
+            carouselControl = control.FindDescendant("CarouselControl") as Carousel;
             carouselControl.ItemsSource = await new Data.PhotosDataSource().GetItemsAsync();
         }
     }

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/DataGrid/DataGridPage.xaml.cs

@@ -35,7 +35,7 @@ public async void OnXamlRendered(FrameworkElement control)
                 dataGrid.LoadingRowGroup -= DataGrid_LoadingRowGroup;
             }
 
-            dataGrid = control.FindDescendantByName("dataGrid") as DataGrid;
+            dataGrid = control.FindDescendant("dataGrid") as DataGrid;
             if (dataGrid != null)
             {
                 dataGrid.Sorting += DataGrid_Sorting;
@@ -54,7 +54,7 @@ public async void OnXamlRendered(FrameworkElement control)
                 groupButton.Click -= GroupButton_Click;
             }
 
-            groupButton = control.FindDescendantByName("groupButton") as AppBarButton;
+            groupButton = control.FindDescendant("groupButton") as AppBarButton;
             if (groupButton != null)
             {
                 groupButton.Click += GroupButton_Click;

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/DockPanel/DockPanelPage.xaml.cs

@@ -9,7 +9,6 @@
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
 using Windows.UI.Xaml.Media;
-using Windows.UI.Xaml.Navigation;
 
 namespace Microsoft.Toolkit.Uwp.SampleApp.SamplePages
 {
@@ -29,7 +28,7 @@ public DockPanelPage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            _sampleDockPanel = control.FindChildByName("SampleDockPanel") as DockPanel;
+            _sampleDockPanel = control.FindChild("SampleDockPanel") as DockPanel;
         }
 
         private void Load()

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/FadeHeader/FadeHeaderBehaviorPage.xaml.cs

@@ -26,7 +26,7 @@ public FadeHeaderBehaviorPage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            myListView = control.FindChildByName("MyListView") as ListView;
+            myListView = control.FindChild("MyListView") as ListView;
 
             // Load the ListView with Sample Data
             if (myListView != null)

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/GazeInteraction/GazeInteractionPage.xaml.cs

@@ -2,13 +2,11 @@
 // 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 Microsoft.Toolkit.Uwp.Input.GazeInteraction;
 using Microsoft.Toolkit.Uwp.UI.Extensions;
 using Windows.UI.Core;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
-using Windows.UI.Xaml.Shapes;
 
 namespace Microsoft.Toolkit.Uwp.SampleApp.SamplePages
 {
@@ -33,7 +31,7 @@ public void OnXamlRendered(FrameworkElement control)
 
             WarnUserToPlugInDevice();
 
-            var buttonControl = control.FindChildByName("TargetButton") as Button;
+            var buttonControl = control.FindChild("TargetButton") as Button;
 
             if (buttonControl != null)
             {

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/GazeTracing/GazeTracingPage.xaml.cs

@@ -42,7 +42,7 @@ public GazeTracingPage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            if (control.FindChildByName("Points") is ItemsControl itemsControl)
+            if (control.FindChild("Points") is ItemsControl itemsControl)
             {
                 itemsControl.ItemsSource = GazeHistory;
             }

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/HeaderedItemsControl/HeaderedItemsControlPage.xaml.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Collections.Generic;
+using System.Linq;
 using Microsoft.Toolkit.Uwp.UI.Controls;
 using Microsoft.Toolkit.Uwp.UI.Extensions;
 using Windows.UI.Xaml;
@@ -26,7 +27,7 @@ public HeaderedItemsControlPage()
 
         public void OnXamlRendered(FrameworkElement element)
         {
-            foreach (var control in element.FindChildren<HeaderedItemsControl>())
+            foreach (var control in element.FindChildren().OfType<HeaderedItemsControl>())
             {
                 control.DataContext = this;
             }

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/ImageCache/ImageCachePage.xaml.cs

@@ -29,7 +29,7 @@ public ImageCachePage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            photoList = control.FindChildByName("PhotoList") as ListView;
+            photoList = control.FindChild("PhotoList") as ListView;
         }
 
         private async void Load()

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/ImageCropper/ImageCropperPage.xaml.cs

@@ -4,12 +4,9 @@
 
 using System;
 using System.Collections.Generic;
-using System.IO;
-using System.Runtime.InteropServices.WindowsRuntime;
 using System.Threading.Tasks;
 using Microsoft.Toolkit.Uwp.UI.Controls;
 using Microsoft.Toolkit.Uwp.UI.Extensions;
-using Windows.Graphics.Imaging;
 using Windows.Storage;
 using Windows.Storage.Pickers;
 using Windows.UI.Xaml;
@@ -35,7 +32,7 @@ public ImageCropperPage()
 
         public async void OnXamlRendered(FrameworkElement control)
         {
-            _imageCropper = control.FindChildByName("ImageCropper") as ImageCropper;
+            _imageCropper = control.FindChild("ImageCropper") as ImageCropper;
             if (_imageCropper != null)
             {
                 var file = await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///Assets/Photos/Owl.jpg"));

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/ImageEx/ImageExPage.xaml.cs

@@ -32,9 +32,9 @@ public ImageExPage()
         public void OnXamlRendered(FrameworkElement control)
         {
             // Need to use logical tree here as scrollviewer hasn't initialized yet even with dispatch.
-            container = control.FindChildByName("Container") as StackPanel;
+            container = control.FindChild("Container") as StackPanel;
             resources = control.Resources;
-            lazyLoadingControlHost = control.FindChildByName("LazyLoadingControlHost") as Border;
+            lazyLoadingControlHost = control.FindChild("LazyLoadingControlHost") as Border;
         }
 
         private async void Load()

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/Implicit Animations/ImplicitAnimationsPage.xaml.cs

@@ -27,7 +27,7 @@ public ImplicitAnimationsPage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            _element = control.FindChildByName("Element");
+            _element = control.FindChild("Element");
         }
 
         private void Load()

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/InAppNotification/InAppNotificationPage.xaml.cs

@@ -35,14 +35,14 @@ public void OnXamlRendered(FrameworkElement control)
         {
             NotificationDuration = 0;
 
-            _exampleInAppNotification = control.FindChildByName("ExampleInAppNotification") as InAppNotification;
+            _exampleInAppNotification = control.FindChild("ExampleInAppNotification") as InAppNotification;
             _defaultInAppNotificationControlTemplate = _exampleInAppNotification?.Template;
-            _exampleCustomInAppNotification = control.FindChildByName("ExampleCustomInAppNotification") as InAppNotification;
+            _exampleCustomInAppNotification = control.FindChild("ExampleCustomInAppNotification") as InAppNotification;
             _customInAppNotificationControlTemplate = _exampleCustomInAppNotification?.Template;
-            _exampleVSCodeInAppNotification = control.FindChildByName("ExampleVSCodeInAppNotification") as InAppNotification;
+            _exampleVSCodeInAppNotification = control.FindChild("ExampleVSCodeInAppNotification") as InAppNotification;
             _resources = control.Resources;
 
-            var notificationDurationTextBox = control.FindChildByName("NotificationDurationTextBox") as TextBox;
+            var notificationDurationTextBox = control.FindChild("NotificationDurationTextBox") as TextBox;
             if (notificationDurationTextBox != null)
             {
                 notificationDurationTextBox.TextChanged += NotificationDurationTextBox_TextChanged;

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/InfiniteCanvas/InfiniteCanvasPage.xaml.cs

@@ -29,7 +29,7 @@ public InfiniteCanvasPage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            _infiniteCanvas = control.FindChildByName("canvas") as InfiniteCanvas;
+            _infiniteCanvas = control.FindChild("canvas") as InfiniteCanvas;
         }
 
         private void Load()

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/ItemsReorderAnimation/ItemsReorderAnimationPage.xaml.cs

@@ -19,7 +19,7 @@ public ItemsReorderAnimationPage()
 
         public async void OnXamlRendered(FrameworkElement control)
         {
-            imageView = control.FindChildByName("ImageView") as GridView;
+            imageView = control.FindChild("ImageView") as GridView;
 
             if (imageView != null)
             {

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/ListViewExtensions/ListViewExtensionsPage.xaml.cs

@@ -24,7 +24,7 @@ public ListViewExtensionsPage()
 
         public async void OnXamlRendered(FrameworkElement control)
         {
-            var sampleListView = control.FindChildByName("SampleListView") as ListView;
+            var sampleListView = control.FindChild("SampleListView") as ListView;
 
             if (sampleListView != null)
             {

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/Loading/LoadingPage.xaml.cs

@@ -24,11 +24,11 @@ public LoadingPage()
 
         public async void OnXamlRendered(FrameworkElement control)
         {
-            loadingControl = control.FindDescendantByName("LoadingControl") as Loading;
-            loadingContentControl = control.FindChildByName("LoadingContentControl") as ContentControl;
+            loadingControl = control.FindDescendant("LoadingControl") as Loading;
+            loadingContentControl = control.FindChild("LoadingContentControl") as ContentControl;
             resources = control.Resources;
 
-            if (control.FindChildByName("AdaptiveGridViewControl") is AdaptiveGridView gridView)
+            if (control.FindChild("AdaptiveGridViewControl") is AdaptiveGridView gridView)
             {
                 gridView.ItemsSource = await new Data.PhotosDataSource().GetItemsAsync();
             }

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/MarkdownTextBlock/MarkdownTextBlockPage.xaml.cs

@@ -31,9 +31,9 @@ public MarkdownTextBlockPage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            unformattedText = control.FindChildByName("UnformattedText") as TextBox;
+            unformattedText = control.FindChild("UnformattedText") as TextBox;
 
-            markdownText = control.FindChildByName("MarkdownText") as MarkdownTextBlock;
+            markdownText = control.FindChild("MarkdownText") as MarkdownTextBlock;
 
             if (markdownText != null)
             {

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/Menu/MenuPage.xaml.cs

@@ -22,7 +22,7 @@ public MenuPage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            fileMenu = control.FindChildByName("FileMenu") as MenuItem;
+            fileMenu = control.FindChild("FileMenu") as MenuItem;
         }
         #pragma warning restore CS0618 // Type or member is obsolete
 

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/OrbitView/OrbitViewPage.xaml.cs

@@ -28,13 +28,13 @@ public OrbitViewPage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            var people = control.FindChildByName("People") as OrbitView;
+            var people = control.FindChild("People") as OrbitView;
             if (people != null)
             {
                 people.ItemClick += People_ItemClick;
             }
 
-            var devices = control.FindChildByName("Devices") as OrbitView;
+            var devices = control.FindChild("Devices") as OrbitView;
             if (devices != null)
             {
                 devices.ItemsSource = DeviceList;

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/PrintHelper/PrintHelperPage.xaml.cs

@@ -10,7 +10,6 @@
 using Windows.UI.Popups;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
-using Windows.UI.Xaml.Navigation;
 
 namespace Microsoft.Toolkit.Uwp.SampleApp.SamplePages
 {
@@ -40,7 +39,7 @@ public PrintHelperPage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            var listView = control.FindChildByName("PrintSampleListView") as ListView;
+            var listView = control.FindChild("PrintSampleListView") as ListView;
             if (listView == null)
             {
                 customPrintTemplate = null;

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/RotatorTile/RotatorTilePage.xaml.cs

@@ -22,28 +22,28 @@ public RotatorTilePage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            var tile1 = control.FindChildByName("Tile1") as RotatorTile;
+            var tile1 = control.FindChild("Tile1") as RotatorTile;
 
             if (tile1 != null)
             {
                 tile1.ItemsSource = _pictures;
             }
 
-            var tile2 = control.FindChildByName("Tile2") as RotatorTile;
+            var tile2 = control.FindChild("Tile2") as RotatorTile;
 
             if (tile2 != null)
             {
                 tile2.ItemsSource = _pictures;
             }
 
-            var tile3 = control.FindChildByName("Tile3") as RotatorTile;
+            var tile3 = control.FindChild("Tile3") as RotatorTile;
 
             if (tile3 != null)
             {
                 tile3.ItemsSource = _pictures;
             }
 
-            var tile4 = control.FindChildByName("Tile4") as RotatorTile;
+            var tile4 = control.FindChild("Tile4") as RotatorTile;
 
             if (tile4 != null)
             {

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/ScrollHeader/ScrollHeaderPage.xaml.cs

@@ -22,7 +22,7 @@ public ScrollHeaderPage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            var listView = control.FindChildByName("listView") as ListView;
+            var listView = control.FindChild("listView") as ListView;
             if (listView != null)
             {
                 listView.ItemsSource = _items;

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/ScrollViewerExtensions/ScrollViewerExtensionsPage.xaml.cs

@@ -30,12 +30,12 @@ public ScrollViewerExtensionsPage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            var listView = control.FindChildByName("listView") as ListView;
+            var listView = control.FindChild("listView") as ListView;
             if (listView != null)
             {
                 listView.ItemsSource = _items;
 
-                var shapesPanel = control.FindChildByName("shapesPanel") as StackPanel;
+                var shapesPanel = control.FindChild("shapesPanel") as StackPanel;
                 if (shapesPanel != null)
                 {
                     var listScrollViewer = listView.FindDescendant<ScrollViewer>();

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/StaggeredLayout/StaggeredLayoutPage.xaml.cs

@@ -34,7 +34,7 @@ public StaggeredLayoutPage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            var repeater = control.FindDescendantByName("StaggeredRepeater") as ItemsRepeater;
+            var repeater = control.FindDescendant("StaggeredRepeater") as ItemsRepeater;
 
             if (repeater != null)
             {

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/StaggeredPanel/StaggeredPanelPage.xaml.cs

@@ -21,7 +21,7 @@ public StaggeredPanelPage()
 
         public async void OnXamlRendered(FrameworkElement control)
         {
-            var gridView = control.FindChildByName("GridView") as ItemsControl;
+            var gridView = control.FindChild("GridView") as ItemsControl;
 
             if (gridView == null)
             {

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/TextBoxMask/TextBoxMaskPage.xaml.cs

@@ -23,7 +23,7 @@ public TextBoxMaskPage()
 
         public void OnXamlRendered(FrameworkElement control)
         {
-            alphaTextBox = control.FindChildByName("AlphaTextBox") as TextBox;
+            alphaTextBox = control.FindChild("AlphaTextBox") as TextBox;
         }
 
         private void Load()