<Grid Margin="10">
  <Grid.ColumnDefinitions>
    <ColumnDefinition />
    <ColumnDefinition Width="Auto"/>
    <ColumnDefinition />
  </Grid.ColumnDefinitions>
  <DataGrid
    AutoGenerateColumns="True"
    IsReadOnly="True"
    ItemsSource="{Binding Items}" />
  <GridSplitter
    Grid.Column="1"
    Width="5" 
    HorizontalAlignment="Center"/>
  <ListBox
    Grid.Column="2"
    ItemsSource="{Binding Items}">
    <ListBox.ItemTemplate>
      <DataTemplate>
        <TextBlock
          Text="{Binding Name}"/>
      </DataTemplate>
    </ListBox.ItemTemplate>
  </ListBox>
</Grid>

public partial class MainWindow
{
  public MainWindow()
  {
    InitializeComponent();
    Items = Enumerable.Range(0, 50).Select(n => new { Id = n, Name = new string((char)(33 + n), n) });
    DataContext = this;
  }

  public IEnumerable Items { get; private set; }
}