"Element '' hat kein übergeordnetes Fenster"

[xZise]

Die Create Methode:

Delphi-Quellcode:

constructor TCompletionMemo.Create(AOwner: TComponent);
begin
   inherited;
  completionBox := TListBox.Create(self);
  completionBox.Parent := AOwner as TWinControl;
  completionBox.Width := FCompletionSizeWidth;
  completionBox.Height := FCompletionSizeHeight;
  FCompletionList := TStringList.Create;
end;

Und ggf. wichtig:
Die Property der ListBox:

Delphi-Quellcode:

  published
    property CompletionList : TStringList read FCompletionList write FCompletionList;