How to use Message.Attach to call methods inside another object - wpf

Question

I have a view model which has another class set as its property. The another class contains implementations of ICommand as its properties. I would like to execute one of the commands on a double click.
Unfortunatelly, Caliburn.Micro raises an exception instead ("No target found for method Commands.Command.Execute.").
I've tried to search the net and read the documentation, but without any success.
How to do it correctly?
Note: In real application, the message might be attached to a grid view which might have a different DataContext than the view model containing the commands class.
The XAML:
<Window x:Class="WpfApplication8.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:cal="http://www.caliburnproject.org">
<Grid>
<TextBox
cal:Message.Attach="[Event MouseDoubleClick]
= [Action Commands.Command.Execute(null)]" />
</Grid>
</Window>
The code-behind class:
namespace WpfApplication8
{
public partial class MainWindow
{
public Commands Commands { get; set; }
public MainWindow()
{
this.Commands =
new Commands { Command = new Command { MainWindow = this } };
this.InitializeComponent();
this.DataContext = this;
}
}
public class Commands
{
public Command Command { get; set; }
}
public class Command
{
public MainWindow MainWindow { get; set; }
public void Execute(object parameter)
{
this.MainWindow.Title = "Executed";
}
}
}

Answer 1

As #alik commented, complete solution is:
<Window x:Class="WpfApplication8.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:cal="http://www.caliburnproject.org">
<Grid>
<TextBox
cal:Message.Attach="[Event MouseDoubleClick] = [Action Execute(null)]"
cal:Action.TargetWithoutContext="{Binding Commands.Command}"/>
</Grid>
</Window>