...
sub zeige_status{    
    
 if (! Exists($statusfenster)){
    $statusfenster=$gui->Toplevel(-width => 400,
                                     -height => 200);
    $statusfenster->title("Status");
    $statusfenster->Label (-text => "Statusfenster")->pack;
    $statusfenster->Button (-text=> "close",
                            -command => [$statusfenster => "destroy"])->pack(-pady=>5
                                                                            );
...
    
}else{
    
   $statusfenster->deiconify();
   $statusfenster->raise();
}