ObservableCollections/sandbox/WpfApp/MainWindow.xaml

<Window x:Class="WpfApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        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"
        xmlns:local="clr-namespace:WpfApp"
        mc:Ignorable="d"
        Title="MainWindow" Height="800" Width="800">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>

        <!-- original -->
        <StackPanel Grid.Row="0" Grid.ColumnSpan="2" Orientation="Vertical">
            <ListBox ItemsSource="{Binding ItemsView}" />
            <Button Content="Add" Command="{Binding AddCommand}" />
            <Button Content="AddRange" Command="{Binding AddRangeCommand}" />
            <Button Content="Insert" Command="{Binding InsertAtRandomCommand}" />
            <Button Content="Remove" Command="{Binding RemoveAtRandomCommand}" />
            <Button Content="RemoveRange" Command="{Binding RemoveRangeCommand}" />
            <Button Content="Clear" Command="{Binding ClearCommand}" />
            <Button Content="Reverse" Command="{Binding ReverseCommand}" />
            <Button Content="Sort" Command="{Binding SortCommand}" />
        </StackPanel>

        <!-- Upper left (NotWritable, NonFilter) -->
        <GroupBox Grid.Row="1" Grid.Column="0" Header="NotWritable, NonFilter">
            <StackPanel Orientation="Vertical">
                <DataGrid ItemsSource="{Binding NotWritableNonFilterView}" />
            </StackPanel>
        </GroupBox>

        <!-- Upper right (Writable, NonFilter) -->
        <GroupBox Grid.Row="1" Grid.Column="1" Header="Writable, NonFilter">
            <StackPanel Orientation="Vertical">
                <DataGrid ItemsSource="{Binding WritableNonFilterPersonView}" />
            </StackPanel>
        </GroupBox>

        <!-- Lower left (NotWritable, Filter) -->
        <GroupBox Grid.Row="2" Grid.Column="0" Header="NotWritable, Filter">
            <StackPanel Orientation="Vertical">
                <DataGrid ItemsSource="{Binding NotWritableFilterView}" />
                <Button Content="AttachFilter" Command="{Binding AttachFilterCommand2}" />
                <Button Content="ResetFilter" Command="{Binding ResetFilterCommand2}" />
            </StackPanel>
        </GroupBox>

        <!-- Lower right (Writable, Filter) -->
        <GroupBox Grid.Row="2" Grid.Column="1" Header="Writable, Filter">
            <StackPanel Orientation="Vertical">
                <DataGrid ItemsSource="{Binding WritableFilterPersonView}" />
                <Button Content="AttachFilter" Command="{Binding AttachFilterCommand3}" />
                <Button Content="ResetFilter" Command="{Binding ResetFilterCommand3}" />
            </StackPanel>
        </GroupBox>

    </Grid>
</Window>