anchor.diff:  
     /// The mouse has moved without any mouse buttons held down. This event is
     /// sent to the [belowmouse] widget. In order to receive [MOVE] events, the
  -  /// widget must return non-zero when handling [ENTER].
  +  /// widget must return true when handling [ENTER].
     MOVE,
   
     /// If the [focus] widget is null or ignores a [KEYBOARD] event then FLTK
     /// tries sending this event to every widget it can, until one of them returns
  -  /// non-zero.
  +  /// true.
     ///
     /// SHORTCUT is first sent to the [belowmouse] widget, then its parents and
     /// siblings, and eventually to every widget in the window, trying to find an
  -  /// object that returns non-zero. FLTK tries really hard to not to ignore any
  +  /// object that returns true. FLTK tries really hard to not to ignore any
     /// keystrokes!
     ///
     /// You can also make global shortcuts by using [addHandler]. A global
  
positive.code:   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
    /// following [PASTE] event.
    DND_RELEASE,
  
  
negative.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 true. 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.
    ///
  