Pursuing my original method, the following almost fixes it, but there is a slight lag when you change direction on the bar drag. If you release the button before changing direction, it's ok.

$yscroll->configure(
      -background => "lightgreen", 
      -troughcolor => "black",
      -command => sub {
          print "@_\n";        
        
         my( $type,$delta,$units )= @_;
        
         if($type eq 'scroll'){
          foreach my $list (@listboxes) {
                $list->yview(@_);
            }
          }
    
         if($type eq 'moveto'){
             my $num = 1;
             if( $delta < 0){$num = -1}         
         
           foreach my $list (@listboxes) {
                $list->yview('scroll',$num,'units');
             }
          }
    },

);
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