MainWindow.cs

using System.Collections.ObjectModel;
using System.Windows;

namespace WpfApplication28
{
    public partial class MainWindow : Window
    {
        public ObservableCollection<MyItem> MyItems { get; set; }

        private void MyListBox_OnPreviewMouseUp(object sender, MouseButtonEventArgs e)
        {
            if (e.OriginalSource.GetType() == typeof(ScrollViewer))
                return;
            
            if (e.ChangedButton == MouseButton.Right && e.ClickCount == 1 && MyListBox.SelectedItems.Count == 1)
            {
                SelectedItem.ShowDetails(null);
            }

            if (e.ChangedButton == MouseButton.Right && e.ClickCount == 1 && MyListBox.SelectedItems.Count > 1)
            {
                var cm = new ContextMenu();
                var mi = new MenuItem();
                mi.Header = "Red";
                cm.Items.Add(mi);
                mi = new MenuItem();
                mi.Header = "Blue";
                cm.Items.Add(mi);
                mi = new MenuItem();
                mi.Header = "Green";
                cm.Items.Add(mi);
                MyListBox.ContextMenu = cm;
                MyListBox.ContextMenu.IsOpen = true;
            }
        }

        public MainWindow()
        {
            InitializeComponent();
            MyItems = new ObservableCollection<MyItem>();
            MyItems.Add(new MyItem("1"));
            MyItems.Add(new MyItem("2"));
            MyItems.Add(new MyItem("3"));
            MyItems.Add(new MyItem("4"));
            MyItems.Add(new MyItem("5"));
            MyItems.Add(new MyItem("6"));
            MyItems.Add(new MyItem("7"));
            MyItems.Add(new MyItem("8"));
            DataContext = this;
        }
    }
}

MainWindow.xaml

<Window x:Class="WpfApplication28.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        
        <ListBox PreviewMouseDown="UIElement_OnPreviewMouseDown" SelectedItem="{Binding SelectedItem}" SelectionMode="Extended" ItemsSource="{Binding MyItems}">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Border BorderBrush="Gray" BorderThickness="1" Width="100" Height="100" Background="Transparent">
                        <!--<Border.InputBindings>
                            <MouseBinding MouseAction="RightClick" Command="{Binding CmdShowDetails}" />
                        </Border.InputBindings>-->
                        <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center" Text="{Binding Name}" />
                    </Border>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
        
    </Grid>
</Window>

MyItem.cs

using System.Windows;
using System.Windows.Input;

namespace WpfApplication28
{
    public class MyItem
    {
        public string Name { get; set; }

        public MyItem(string name)
        {
            Name = name;
        }

        private RelayCommand _showDetails;
        public ICommand CmdShowDetails { get { return _showDetails ?? (_showDetails = new RelayCommand(ShowDetails)); } }

        public void ShowDetails(object o)
        {
            MessageBox.Show("details for: " + Name);
        }
    }
}