anchor.diff:      use dynamicVm = new DesktopBindingTarget()
       dynamicVm.BindView "Test" v2
   
  -    let obs = PropertyChangedObserver()
  -    obs.Subscribe dynamicVm
  +    let obs = PropertyChangedObserver(dynamicVm)    
       
       let props = TypeDescriptor.GetProperties(dynamicVm)
       let prop = props.Find("Test", false)
  
positive.code:         |> Bind.edit "Last" last
          |> Bind.watch "Full" full
  
      let obs = PropertyChangedObserver()
      obs.Subscribe dynamicVm
  
      Assert.AreEqual(0, obs.["Full"])        
  
  
negative.code:     override __.BindCommand name comm =
          ()
  
  type PropertyChangedObserver(o : INotifyPropertyChanged) =
      let changes = System.Collections.Generic.Dictionary<string,int>()
  
      do
          o.PropertyChanged.Add(fun args ->            
              let current = 
                  match changes.ContainsKey args.PropertyName with
  