# first way with tags, all outer balls will be bound
# to same callback
my $refitem = $zinc->add('arc',$centergroup2, [ [10,20], [20,30] ],
               -filled => 1,
               -fillcolor => $refgrad,              ##    $refgrad
               -linewidth => 0,
               -priority => 100
               -tags => ['outerring'],
               );

# make/clone 11/12 more of the above
for (1..11){
  my $relement = $zinc->clone($refitem);
  $zinc->rotate($relement,.53*$_);
}

$zinc->bind( 'outerring', '<1>',  \&ro6);