function TControl.DblBufTopParent: PControl;
var Ctl: PControl;
begin
  Result := nil;
//  Ctl := @ Self;
  Ctl := Self;
  while Ctl <> nil do
  begin
    if Ctl.fDoubleBuffered then
      Result := Ctl;
    if Ctl.isForm then exit;
    Ctl := Ctl.fParent;
  end;
end;