public class MetroPopupWindowAction:PopupWindowAction
    {
        protected override Window CreateWindow()
        {
            return new MessageDialogWindow();
        }
    }

<!--Window1 Dialog-->
        <prism:InteractionRequestTrigger SourceObject="{Binding Window1DialogRequest}">
            <util:MetroPopupWindowAction IsModal="True" CenterOverAssociatedObject="True">
                <util:MetroPopupWindowAction.WindowContent>                   
                    <local:Window1/>
                </util:MetroPopupWindowAction.WindowContent>
            </util:MetroPopupWindowAction>
        </prism:InteractionRequestTrigger>

private void OK()
        {
            Window1DialogRequest.Raise(new Window1DialogModel { Str = $"6666", Title = "Window1" }, _ =>
            {
                MessageBox.Show(_.Str);
            });
        }
        #endregion

        #region NotificationRequest
        public InteractionRequest<Window1DialogModel> Window1DialogRequest { get; set; }
        #endregion

        public ExportMainWindowViewModel()
        {
            Window1DialogRequest = new InteractionRequest<Window1DialogModel>();
        }