WPF

<ContextMenu>
  <MenuItem Command="{Binding MyCommand}" />
  <ContextMenu.ItemContainerStyle>
    <Style TargetType="MenuItem">
      <Setter Property="Header" Value="Item" />
      <Setter Property="CommandParameter" Value="ValidParameter" />
    </Style>
  </ContextMenu.ItemContainerStyle>
</ContextMenu>

<Window x:Class="CommandParameterExample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        DataContext="{Binding RelativeSource={RelativeSource Self}}">

  <StackPanel>
    <Border Margin="4" Height="50" Background="Green">
      <Border.ContextMenu>
        <ContextMenu>
          <MenuItem Command="{Binding MyCommand}" />
          <ContextMenu.ItemContainerStyle>
            <Style TargetType="MenuItem">
              <Setter Property="Header" Value="Item" />
              <Setter Property="CommandParameter" Value="ValidParameter" />
            </Style>
          </ContextMenu.ItemContainerStyle>
        </ContextMenu>
      </Border.ContextMenu>
    </Border>
  </StackPanel>
</Window>

using System;
using System.Diagnostics;
using System.Linq;
using System.Windows.Input;

namespace CommandParameterExample
{
    public partial class MainWindow
    {
        public ICommand MyCommand { get; private set; }

        public MainWindow()
        {
            MyCommand = new CommandModel();
            InitializeComponent();
        }
    }

    internal class CommandModel : ICommand
    {
        public bool CanExecute(object parameter)
        {
            WriteParameter(parameter, "CanExecute");
            return true;
        }

        public void Execute(object parameter)
        {
            WriteParameter(parameter, "Execute");
        }

        private static void WriteParameter(object parameter, string context)
        {
            Debug.WriteLine("Parameter in {0}: {1}", context, parameter ?? "null");
        }

        public event EventHandler CanExecuteChanged;
    }
}

<Page.Resources>
  <my:Chart x:Key="chart"/>
</Page.Resources>

...

<DynamicResource ResourceKey="chart"/>

<Window x:Class="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>
        <Grid.Resources>
            <DataTemplate x:Key="SystemTemplate">
                <Label Content="{Binding XPath=Name}"/>
            </DataTemplate>
        </Grid.Resources>
        <Grid.DataContext>
            <XmlDataProvider x:Name="SystemData" Source="Systems.xml" XPath="Emulators/System" />
        </Grid.DataContext>
        <ListBox Height="244" HorizontalAlignment="Left" Margin="12,12,0,0" Name="ListBox1" VerticalAlignment="Top" Width="167"
                 ItemsSource="{Binding}"
                 ItemTemplate="{StaticResource SystemTemplate}"
                 IsSynchronizedWithCurrentItem="True"
                 Visibility="Visible" SelectionMode="Single">
         </ListBox>
    </Grid>
</Window>