Fixed incorrect blur in loading sample

Author: Sergio0694

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/Loading/LoadingCode.bind

@@ -37,7 +37,7 @@
 
   <Grid>
 
-    <ScrollViewer>
+    <ScrollViewer x:Name="ScrollViewerControl">
       <StackPanel Margin="20">
         <RichTextBlock Margin="0,10,0,0">
           <Paragraph FontSize="18" FontWeight="Bold">The loading control is for showing an animation with some content when the user should wait in some tasks of the app.</Paragraph>

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

@@ -13,6 +13,7 @@ namespace Microsoft.Toolkit.Uwp.SampleApp.SamplePages
 {
     public sealed partial class LoadingPage : IXamlRenderListener
     {
+        private ScrollViewer scrollViewerControl;
         private AdaptiveGridView adaptiveGridViewControl;
         private Loading loadingControl;
         private ContentControl loadingContentControl;
@@ -26,6 +27,7 @@ public LoadingPage()
 
         public async void OnXamlRendered(FrameworkElement control)
         {
+            scrollViewerControl = control.FindChildByName("ScrollViewerControl") as ScrollViewer;
             adaptiveGridViewControl = control.FindChildByName("AdaptiveGridViewControl") as AdaptiveGridView;
             loadingControl = control.FindDescendantByName("LoadingControl") as Loading;
             loadingContentControl = control.FindChildByName("LoadingContentControl") as ContentControl;
@@ -62,9 +64,13 @@ private void Load()
                 if (loadingContentControl != null)
                 {
                     loadingContentControl.ContentTemplate = resources["LogoTemplate"] as DataTemplate;
-                    await loadingContentControl.Blur(2, 100).StartAsync();
+
+                    // We need to blur the ScrollViewer hosting the main content of the page and not the
+                    // root control, otherwise the popup with the icon would be blurred as well, as it
+                    // would be in the same visual tree as the control whose visual is being blurred.
+                    await scrollViewerControl.Blur(2, 100).StartAsync();
                     await ShowLoadingDialogAsync();
-                    await loadingContentControl.Blur(0, 0).StartAsync();
+                    await scrollViewerControl.Blur(0, 0).StartAsync();
                 }
             });
         }