anchor.diff:  
     TMessage = class (TTagged, IMessage)
       sym : TSymbol;
  -    sender: TActor;
  +    sender: IActor;
       args: TTuple;
     end;
   
  
positive.code:              end;
        else
          msg := TEvent.Create(evt_keydn, ord(ch));
          if assigned(focus) then
  	  if (focus is TActor)
  	    and not (focus as TActor).handle(msg)
  	    then pass; {--  TODO: global keymap --}
  	msg.Free;
        end; { case }
    end;
  
  
negative.code:     property alive:boolean read GetAlive;
      procedure Halt;
      procedure Draw;
      function ToString : String;
    end;
    IGroup = interface (IActor)
      procedure Add( child : IActor );
  