using Prism.Interactivity.InteractionRequest;
using System.Windows;
using System.Windows.Interactivity;

namespace Sample.ViewUtilities {
    public class CloseWindowAction : TriggerAction<DependencyObject> {
        protected override void Invoke(object parameter) {
            if (parameter is InteractionRequestedEventArgs e) {
                Invoke(AssociatedObject, e);
            }
        }

        private void Invoke(DependencyObject sender,
            InteractionRequestedEventArgs e) {
            if (sender is Window window) {
                window.Close();
                e.Callback?.Invoke();
            }
        }
    }
}

public InteractionRequest<Notification> CloseWindowRequest { get; private set; }
public DelegateCommand CloseWindowCommand { get; private set; }

public SampleWindowViewModel() {
    CloseWindowRequest = new InteractionRequest<Notification>();
    CloseWindowCommand = new DelegateCommand(ExecuteCloseWindowCommand,
        CanExecuteCloseWindowCommand);
}

private bool CanExecuteCloseWindowCommand() {
    return true;
}

private void ExecuteCloseWindowCommand() {
    CloseWindowRequest.Raise(null);
}

xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:prism="http://www.codeplex.com/prism"
xmlns:ViewUtilities="clr-namespace:Sample.ViewUtilities"
・・・
<i:Interaction.Triggers>
  <prism:InteractionRequestTrigger
    SourceObject="{Binding CloseWindowRequest}">
    <ViewUtilities:CloseWindowAction/>
  </prism:InteractionRequestTrigger>
</i:Interaction.Triggers>
・・・
<Window.InputBindings>
  <KeyBinding Modifiers="Ctrl" Key="W"
    Command="{Binding CloseWindowCommand, Mode=OneWay}"/>
</Window.InputBindings>
・・・
<Menu>
  <MenuItem Header="ファイル(_F)">
    <MenuItem Header="閉じる(_X)"
      Command="{Binding CloseWindowCommand, Mode=OneWay}"/>
  </MenuItem>
</Menu>