Presentation Model (MVVM) Good Practices

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

namespace PresentationModelBase
{
    /// <summary>
    /// This class represents an UI Widget that 
    /// can be removed from the screen.
    /// </summary>
    public abstract class ClosableViewPresentationModel : PresentationModel, IClosableViewPresentationModel
    {
        public ClosableViewPresentationModel()
        {
            _dialogServicesProvider = Get<IDialogSystem>();
        }

        #region Fields

        IDialogSystem _dialogServicesProvider;

        #endregion

        #region Methods

        public void Close()
        {
            OnRequestClose();
        }

        #endregion

        #region Events

        private EventHandler _handler;
        public event EventHandler RequestClose
        {
            add { _handler += value; }
            remove { _handler -= value; }
        }

        protected virtual void OnRequestClose()
        {
            if (_handler != null)
                _handler(this, EventArgs.Empty);
            Dispose();
        }

        #endregion

        protected QuestionResult AskQuestion(string question)
        {
            return _dialogServicesProvider.AskQuestion(question);
        }

        protected QuestionResult AskQuestion(string question, string title)
        {
            return _dialogServicesProvider.AskQuestion(question, title);
        }

        protected FileInfo ChooseFile(string title)
        {
            return _dialogServicesProvider.ChooseFile(title, null);
        }

        protected FileInfo ChooseImage()
        {
            return _dialogServicesProvider.ChooseImage();
        }

        protected FileInfo ChooseImage(string title)
        {
            return _dialogServicesProvider.ChooseImage(title);
        }
    }
}