title: how to show a message box in a wpf mvvm application?
body: <p>I have an application whch is written in WPF and is based on MVVM. </p>
  
  <p>In part of this application, I am doing a very long processing and at the end of it I want to ask a question from user such as processing finished, do you want to reset data?</p>
  
  <p>I am doing this by showing a message box and it do the job, but I belive it is not a good solution as my ViewModel showing something to user .</p>
  
  <p>What is the best way to implement such messagebox?</p>
  
  <p>I read the answer to similar questions here but all of them related to input validation, whish is not the case here. In my case, I am asking a question which is not related to data validation and hence data vlidation methods doesn't work here.</p>