anchor.diff:          base.OnHandleCreated(e)
           loaded <- true
           base.MakeCurrent()
  -
  -        x.KeyDown.Add(fun e ->
  -            if e.KeyCode = System.Windows.Forms.Keys.End && e.Control then
  -                renderContiuously <- not renderContiuously
  -                x.Invalidate()
  -                e.Handled <- true
  -        )
  -
            
       member x.Render() = 
           if loaded then
  
positive.code:                 f()
  
      member private x.ForceRedraw() =
          if renderContiuously then () 
          else messageLoop.Draw x
  
  
      member x.RenderTask
  
negative.code:     interface IControl with
          member x.IsInvalid = needsRedraw
          member x.Invalidate() =
              if not x.IsDisposed && not renderContinuously then
                  if not needsRedraw then
                      needsRedraw <- true
                      x.Invalidate()
  
          member x.Paint() =
              if not x.IsDisposed && not renderContinuously then
                  use g = x.CreateGraphics()
                  use e = new PaintEventArgs(g, x.ClientRectangle)
                  x.InvokePaint(x, e)
  