add repro for treeview issue.

samples/ControlCatalog/Pages/TreeViewPage.xaml

@@ -11,7 +11,7 @@
                 HorizontalAlignment="Center"
                 Spacing="16">
       <StackPanel Orientation="Vertical" Spacing="8">
-        <TreeView ItemsSource="{Binding Items}" SelectedItems="{Binding SelectedItems}" SelectionMode="{Binding SelectionMode}" Width="250" Height="350">
+        <TreeView ItemsSource="{Binding Items}" SelectedItems="{Binding SelectedItems}" SelectedItem="{Binding SelectedItem}" SelectionMode="{Binding SelectionMode}" Width="250" Height="350">
           <TreeView.ItemTemplate>
             <TreeDataTemplate ItemsSource="{Binding Children}">
               <TextBlock Text="{Binding Header}"/>
@@ -19,6 +19,11 @@
           </TreeView.ItemTemplate>
         </TreeView>
 
+        <StackPanel Orientation="Horizontal">
+          <TextBlock Text="SelectedItem: " />
+          <TextBlock Text="{Binding SelectedItem.Header}" />
+        </StackPanel>
+
         <Button Command="{Binding AddItemCommand}">Add</Button>
         <Button Command="{Binding RemoveItemCommand}">Remove</Button>
         <Button Command="{Binding SelectRandomItemCommand}">Select Random</Button>

samples/ControlCatalog/ViewModels/TreeViewPageViewModel.cs

@@ -10,6 +10,7 @@ namespace ControlCatalog.ViewModels
     {
         private readonly Node _root;
         private SelectionMode _selectionMode;
+        private Node _selectedItem;
 
         public TreeViewPageViewModel()
         {
@@ -25,6 +26,13 @@ namespace ControlCatalog.ViewModels
 
         public ObservableCollection<Node> Items { get; }
         public ObservableCollection<Node> SelectedItems { get; }
+
+        public Node SelectedItem
+        {
+            get => _selectedItem;
+            set => this.RaiseAndSetIfChanged(ref _selectedItem, value);
+        }
+
         public MiniCommand AddItemCommand { get; }
         public MiniCommand RemoveItemCommand { get; }
         public MiniCommand SelectRandomItemCommand { get; }
@@ -47,12 +55,7 @@ namespace ControlCatalog.ViewModels
 
         private void RemoveItem()
         {
-            while (SelectedItems.Count > 0)
-            {
-                Node lastItem = (Node)SelectedItems[0];
-                RecursiveRemove(Items, lastItem);
-                SelectedItems.RemoveAt(0);
-            }
+            SelectedItem?.Parent?.RemoveItem(SelectedItem);
 
             bool RecursiveRemove(ObservableCollection<Node> items, Node selectedItem)
             {