title: Add ContextMenu under ComboBox in c#, when user click of left mouse press on combobox, it shows context menu
body: <p>Here is the code in Xaml and it works, add context menu under combobox</p>
  
  <pre><code>private void cboSingleSite_PreviewMouseDown(object sender, MouseButtonEventArgs e)
  {
      if (e.ChangedButton == MouseButton.Left)
      {
          ComboBox image = sender as ComboBox;
          ContextMenu contextMenu = image.ContextMenu;
          contextMenu.PlacementTarget = image;
          contextMenu.IsOpen = true;
      }
   }
  </code></pre>
  
  <p>Here is the code in C# but not works help me.</p>
  
  <pre><code>private void cboSingleSite_PreviewMouseDown(object sender, MouseEventArgs e)
  {
      if (e.Button == MouseButtons.Left)
      {
          ComboBox combo = sender as ComboBox;
          ContextMenu contextMenu = combo.ContextMenu;
          //ContextMenu cm = (ContextMenu)ContextMenu.ItemsControlFromItemContainer((MenuItem)e.OriginalSource);
          //combo.DisplayMember = "Text";
          combo.Items.Add(contextMenu);
      }
  }
  </code></pre>
  
  <p>I am trying but can't make this work.</p>