If you look at my KeyBehavior you notice that it is doing two things: register for events so that the behavior can be triggered and handle the actual command invocation. In order to enhance reuse we can refactor this KeyBehavior in a KeyTrigger and an InvokeCommandAction. Well, we’re not going to do that, because they exist already in the silverlight sdk 
A shortcoming of the InvokeCommandAction is that it can only invoke commands on the FrameworkElement itself, thus we write a custom implementation that finds commands on the DataContext instead:
public class InvokeCommandAction : TriggerAction<FrameworkElement>
{
public string CommandName { get; set; }
protected override void Invoke(object parameter)
{
var viewModel = AssociatedObject.DataContext;
GetCommandAndExecuteIt(viewModel, CommandName);
}
void GetCommandAndExecuteIt(object viewModel, string commandName)
{
var command = viewModel.GetPropertyValue<ICommand>(commandName);
if(command.CanExecute(null)) command.Execute(null);
}
}
And now we can drag this action on our design surface in Blend and select a trigger that goes with it:
All we have to do is choose the Key and Command to invoke:
In XAML this looks like:
<interactivity:Interaction.Triggers> <ii:KeyTrigger Key="Right"> <inf:InvokeCommandAction CommandName="PlayerRight"/> </ii:KeyTrigger> <ii:KeyTrigger Key="Left"> <inf:InvokeCommandAction CommandName="PlayerLeft"/> </ii:KeyTrigger> <ii:KeyTrigger Key="Up"> <inf:InvokeCommandAction CommandName="PlayerUp"/> </ii:KeyTrigger> <ii:KeyTrigger Key="Down"> <inf:InvokeCommandAction CommandName="PlayerDown"/> </ii:KeyTrigger> </interactivity:Interaction.Triggers>
I guess this ends our exploration of the behavior features in Silverlight.