procedure TForm1.PanelMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftstate; x, y: Integer);
var
 Control : TControl;
 i: integer;
begin
 for i := 0 to TPanel(Sender).ControlCount-1 do
 begin
  with TPanel(Sender).Controls[i] do
  begin
   If (x < left) or (x > Left+Width) and (y < top) or (y > Top+Height) then exit else visible := true; // Überprüfung

  end;
 end;
end;