entrance-testing/EntranseTesting/Views/EditorViews/EditorArrangement.axaml

<UserControl xmlns="https://github.com/avaloniaui"
             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"
             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
             x:Class="EntranseTesting.EditorArrangement"
             x:DataType="vm:MainWindowViewModel"
             xmlns:vm="using:EntranseTesting.ViewModels">
  <StackPanel Orientation="Vertical" Spacing="10">
    <StackPanel Orientation="Vertical" Spacing="5">
      <TextBlock Text="Положение элементов" VerticalAlignment="Center"/>
      <ComboBox Width="450"
                ItemsSource="{Binding EditorPages.TaskEditorPage.ArrangmentCategory}"
                SelectedItem="{Binding EditorPages.TaskEditorPage.SelectedArrangmentCategory}"/>
    </StackPanel>

    <ItemsRepeater ItemsSource="{Binding EditorPages.TaskEditorPage.ArrangementElement}"
                               HorizontalAlignment="Stretch"
                               VerticalAlignment="Stretch">
      <ItemsRepeater.Layout>
        <StackLayout Spacing="5" Orientation="Vertical"/>
      </ItemsRepeater.Layout>
      <ItemsRepeater.ItemTemplate>
        <DataTemplate>
          <WrapPanel Orientation="Horizontal">           
            <Button Content="х"
                    Command="{Binding  $parent[Window].((vm:MainWindowViewModel)DataContext).EditorPages.TaskEditorPage.DeleteItem}"
                    CommandParameter="{Binding}"
                    IsVisible="{Binding $parent[Window].((vm:MainWindowViewModel)DataContext).EditorPages.TaskEditorPage.NoEditing}"
                    VerticalAlignment="Center" />
            <NumericUpDown Value="{Binding Position}" Margin="10 0"
                           MinWidth="150" Minimum="1" 
                           Maximum="{Binding $parent[ItemsRepeater].Children.Count}"/>
            <TextBox Text="{Binding Name}"
                     Width="300" Height="80"/>
          </WrapPanel>
        </DataTemplate>
      </ItemsRepeater.ItemTemplate>
    </ItemsRepeater>

    <Button Content="Добавить вариант ответа"
            IsVisible="{Binding EditorPages.TaskEditorPage.NoEditing}"
            Command="{Binding  $parent[Window].((vm:MainWindowViewModel)DataContext).EditorPages.TaskEditorPage.AddItem}"
            HorizontalAlignment="Center"/>
  </StackPanel>
</UserControl>