title: how to implement observable int in wpf ViewModel?
body: <p>In my mvvm ViewModel I have such field</p>
  
  <pre><code>public int Delta { get; private set; }
  </code></pre>
  
  <p>However when I update it like that:</p>
  
  <pre><code>Delta = newValue;
  </code></pre>
  
  <p>UI is not refreshed.</p>
  
  <p>I was thinking that databinding will do that for me. For example I can declare collection as <code>ObservableCollection</code> and then databinding will work.</p>
  
  <p>However there are no <code>ObservableInt</code>, how to say View that it need to be refreshed then?</p>
  
  <p>Probably I should raise some event "notify property changed" or something?</p>