Create a style that will produce a horizontal ListBox.

   
  

<Window Background="cornsilk"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    x:Class="ListBox_Index.Window1">

  <Grid>
    <Grid.ColumnDefinitions>
      <ColumnDefinition/>
      <ColumnDefinition/>
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
      <RowDefinition/>
      <RowDefinition/>
      <RowDefinition/>
      <RowDefinition/>
      <RowDefinition/>
      <RowDefinition/>
      <RowDefinition/>
    </Grid.RowDefinitions>

    <Grid.Resources>
      <Style TargetType="Separator">
        <Setter Property="Template">
          <Setter.Value>
            <ControlTemplate TargetType="{x:Type Separator}">
              <Border Width="2" Height="12" Margin="4" Background="Gray"/>
            </ControlTemplate>
          </Setter.Value>
        </Setter>
      </Style>

      <Style TargetType="ListBox">
        <Setter Property="ItemsPanel">
          <Setter.Value>
            <ItemsPanelTemplate>
              <StackPanel Orientation="Horizontal"
                          VerticalAlignment="Center"
                          HorizontalAlignment="Center"/>
            </ItemsPanelTemplate>
          </Setter.Value>
        </Setter>
      </Style>
      
    </Grid.Resources>

    <ListBox Name="lb" Margin="10" Height="50" Grid.Column="0" Grid.Row="2" Grid.RowSpan="2" SelectionChanged="PrintText">
      <ListBoxItem>Item 1</ListBoxItem>
      <Separator/>
      <ListBoxItem>Item 2</ListBoxItem>
      <Separator/>
      <ListBoxItem>Item 3</ListBoxItem>
      <Separator/>
      <ListBoxItem>Item 4</ListBoxItem>
      <Separator/>
      <ListBoxItem>Item 5</ListBoxItem>
      <Separator/>
      <ListBoxItem>Item 6</ListBoxItem>
      <Separator/>
      <ListBoxItem>Item 7</ListBoxItem>
      <Separator/>
      <ListBoxItem>Item 8</ListBoxItem>
      <Separator/>
      <ListBoxItem>Item 9</ListBoxItem>
      <Separator/>
      <ListBoxItem>Item 10</ListBoxItem>
    </ListBox>
    <Label Margin="10, 10, 3, 3" Name="label1" Grid.Column="0" Grid.Row="5"/>


  </Grid>
</Window>
//File:Window.xaml.cs

using System;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Windows.Data;

namespace ListBox_Index
{
  public partial class Window1 : Window
  {
      public Window1()
      {
        InitializeComponent();
      }  
        private void PrintText(object sender, SelectionChangedEventArgs args){
            ListBoxItem lbi = ((sender as ListBox).SelectedItem as ListBoxItem);
            if( lbi == null ) return;
            label1.Content = "You chose " + lbi.Content.ToString() + "."; 
        } 
    }
}