title: INotifyPropertyChanged doesnt fire when property changes
body: <p>I have a bool value that gets updated and the INotifyPropertyChanged event doesnt fire properly. It gets to the IF portion and steps over because it sees a null being passed. I did add using System.ComponentModel at the top of the class</p>
  
  <p>The first portion:</p>
  
  <pre><code>  public class ToolTipInortfyPropertyChange : INotifyPropertyChanged
  {
  
  
      private bool form15TooltipShow;
      public bool Form15TooltipShow
      {
          get { return form15TooltipShow; }
          set
          {
              form15TooltipShow = value;
              OnPropertyChanged("Form15TooltipShow");
          }
  
      }
  </code></pre>
  
  <p>and then the second portion all in the same class</p>
  
  <pre><code> public void OnPropertyChanged(string propertyName)
      {
          if (PropertyChanged != null)
          {
              PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
          }
      }
  
      public event PropertyChangedEventHandler PropertyChanged;
  </code></pre>
  
  <p>when I step in the code it gets to the "Set" portion then jumps to the OnPropertyChanged and skips the if so my view doesnt get updated with another event needing the bool</p>
  
  <p>Tx</p>