anchor.diff:  
   type MainModel() = 
       member val Value = new ReactiveProperty<int>(0)
  -    
  +
   (**
   ### View
   The view is split in two parts: the form itself and the Qualia View.
  
positive.code:         [ mw.ButtonUp.Click |> Observable.mapTo Up // map first button clicked event
            mw.ButtonDown.Click |> Observable.mapTo Down // second one
            mw.TextBox.TextChanged |> Observable.map (fun e -> Edit mw.TextBox.Text) ] // map textchanged events
      
  (**
  SetBindings subscribe to property changes in the model and updates the ui accordingly.
  In this case, when the model value changes, we set both the label and the textbox content
  
negative.code: - a dispatcher, handling these events and transforming the model
  - an event loop, wiring all previous types
  
  The example is a simple winforms numeric up down. The final app will look like this:
  
  ![numericupdown](img/numericupdown.png)
  
  The + and - buttons increment or decrement the value, which is displayed in a label and a textbox. Changin the value in the textbox will update the value if it can be parsed to an int.
  
  ### Event type
  