Editable combobox overwrites my context menu

Question

I implemented a editable ComboBox with XAML which should show my own context menu:

<ComboBox IsEditable="True"
          ContextMenu="{StaticResource contextMenu}"
          ContextMenuClosing="contextClosing">
    <ComboBoxItem Content="Item1" />
    <ComboBoxItem Content="Item2" />
</ComboBox>

but instead of showing my context menu, it shows the edit context menu (with Cut, Copy & Paste).

Is there a way to overwrite the editable context menu?

Answer 1

The textbox of the editable part must be loaded to overwrite the standard context menu:

<ComboBox IsEditable="True" ContextMenuService.ShowOnDisabled="True" 
     Name="combobox" Loaded="combobox_Loaded">
     <ComboBox.ContextMenu>
         <ContextMenu>
            <MenuItem Header="test"></MenuItem>
         </ContextMenu>
     </ComboBox.ContextMenu>
     <ComboBoxItem Content="Item1"></ComboBoxItem>
     <ComboBoxItem Content="Item2"></ComboBoxItem>
</ComboBox>  

 private void combobox_Loaded(object sender, RoutedEventArgs e)
 {
   (VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(combobox, 0), 2) as TextBox).ContextMenu = combobox.ContextMenu;
 }