anchor.diff:    DND_LEAVE,
   
     /// The user has released the mouse button dropping data into the widget. If
  -  /// the widget returns 1, it will receive the data in the immediately
  +  /// the widget returns true, it will receive the data in the immediately
     /// following [PASTE] event.
     DND_RELEASE,
   
  
positive.code:   ///
    /// The key can be found in [eventKey]. The text that the key should insert
    /// can be found with [eventText]. If you use the key [Widget.handle] should
    /// return 1. If you return zero then FLTK assumes you ignored the key and
    /// will then attempt to send it to a parent widget. If none of them want it,
    /// it will change the event into a [SHORTCUT] event.
    ///
  
negative.code:   MOUSEWHEEL,
  
    /// The mouse has been moved to point at this widget. A widget that is
    /// interested in receiving Drag And Drop data must return true to receive
    /// [DND_DRAG], [DND_LEAVE] and [DND_RELEASE] events.
    DND_ENTER,
  
  