[Lazarus] Declaration of an event type inside a class

[Werner Pamler]

The TAChart code contains a strange declaration:

   TChart = class(TCustomChart, ICoordTransformer)
   public
   type
     TDrawEvent = procedure (ASender: TChart; ADrawer: IChartDrawer) of 
object;
   strict private // Property fields
     FOnAfterDraw: TDrawEvent;
     ....
   published
     property OnAfterDraw: TDrawEvent read FOnAfterDraw write 
SetOnAfterDraw;

The declaration of TDrawEvent is part of the TChart declaration! As 
reported in the German Lazarus forum 
(http://www.lazarusforum.de/viewtopic.php?f=18&t=8474), an error "Unable 
to show method..." is generated because of this construction: If I move 
the TDrawEvent out of the TChart context everything works fine.

I cannot reach Alexander S Klenin for clarification. But what could have 
been his intention of doing it this way? (Or maybe it is just a typo?)