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: - 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
  
negative.code:         addAt x.ButtonDown 1 1
          addAt x.TextBox 0 0
          addAt x.Label 0 1
  
  (**
  #### Qualia View
  The actual Form backing the view. all exposed members will be used by the view.
  