my $button_update = $update->Button(-text    => 'Update suchen', -relief => "raised",
                           -command =>
                             sub        {       
                                                                        $listbox->addOptions("0.9.2","0.9.3","0.9.4");
                                                                        $button_update->configure(-text => "Installieren");
                                                                        },
                        )->place( -x => 22, -y => 71, -width => 251, -height => 44);