Simplifies PaneControl code by removing unnecessary dynamic xaml. (#9120)

Author: cinqmilleans

src/Files.Uwp/UserControls/Pane/PaneControl.xaml

@@ -4,8 +4,13 @@
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-    d:DesignWidth="400" d:DesignHeight="300" mc:Ignorable="d">
+    d:DesignHeight="300"
+    d:DesignWidth="400"
+    mc:Ignorable="d">
 
-    <Grid x:Name="Panel" />
+    <ContentControl
+        x:Name="Panel"
+        HorizontalContentAlignment="Stretch"
+        VerticalContentAlignment="Stretch" />
 
 </UserControl>

src/Files.Uwp/UserControls/Pane/PaneControl.xaml.cs

@@ -8,34 +8,32 @@ namespace Files.Uwp.UserControls
 {
     public sealed partial class PaneControl : UserControl, IPane
     {
-        public PanePositions Position { get; private set; } = PanePositions.None;
+        private PaneContents content;
 
-        private IPaneSettingsService PaneService { get; } = Ioc.Default.GetService<IPaneSettingsService>();
+        private IPaneSettingsService PaneSettingsService { get; } = Ioc.Default.GetService<IPaneSettingsService>();
 
-        private PaneContents content;
-        private Control pane;
+        public PanePositions Position => Panel.Content is IPane pane ? pane.Position : PanePositions.Right;
 
         public PaneControl()
         {
             InitializeComponent();
 
-            PaneService.PropertyChanged += PaneService_PropertyChanged;
+            PaneSettingsService.PropertyChanged += PaneService_PropertyChanged;
             Update();
         }
 
         public void UpdatePosition(double panelWidth, double panelHeight)
         {
-            if (pane is IPane p)
+            if (Panel.Content is IPane pane)
             {
-                p.UpdatePosition(panelWidth, panelHeight);
-                Position = p.Position;
+                pane.UpdatePosition(panelWidth, panelHeight);
             }
-            if (pane is not null)
+            if (Panel.Content is Control control)
             {
-                MinWidth = pane.MinWidth;
-                MaxWidth = pane.MaxWidth;
-                MinHeight = pane.MinHeight;
-                MaxHeight = pane.MaxHeight;
+                MinWidth = control.MinWidth;
+                MaxWidth = control.MaxWidth;
+                MinHeight = control.MinHeight;
+                MaxHeight = control.MaxHeight;
             }
         }
 
@@ -49,17 +47,11 @@ private void PaneService_PropertyChanged(object sender, PropertyChangedEventArgs
 
         private void Update()
         {
-            var newContent = PaneService.Content;
+            var newContent = PaneSettingsService.Content;
             if (content != newContent)
             {
                 content = newContent;
-                pane = GetPane(content);
-
-                Panel.Children.Clear();
-                if (pane is not null)
-                {
-                    Panel.Children.Add(pane);
-                }
+                Panel.Content = GetPane(content);
             }
         }