use Data::Dumper;
our @ISA = ('Tk::Frame');
Tk::Widget->Construct('MyScrollableEdit');
sub Populate{
    my $self = shift;
    my $args = $_[0];
    my $data = delete($args->{-data}) || [];
    my $rows = delete($args->{-rows}) || 10;
    $self->SUPER::Populate($args);
    my @labels = ();
    my @entries = ();
    for (0..$rows-1){
        my $l = $self->Label(-textvariable  => \$data->[$_]{label},
                             -anchor=> 'e'
		        );
        my $w = $self->Entry(-textvariable => \$data->[$_]{value});
        $l->grid($w,-sticky=>'e',
		 -pady=>3,
		 -padx=>2);
        $w->gridConfigure(-sticky=>'ew');
        push @labels, $l;
        push @entries, $w;
    }
    $self->ConfigSpecs(-data   => ['PASSIVE', undef, undef, $data],
                       -rows   => ['PASSIVE', undef, undef, $rows],
                       -labels => ['PASSIVE',undef, undef, \@labels],
                       -entries=> ['PASSIVE',undef, undef, \@entries],
                       -offset => ['PASSIVE',undef, undef, 0],
                   );
}
sub yview{
    my $self = shift;
    #print Dumper \@_;
    my $sb = shift;
    my $data = $self->cget('-data');
    my $rows = $self->cget('-rows');
    my $entries = $self->cget('-entries');
    my $labels = $self->cget('-labels');
    my $offset = $self->cget('-offset');
    my $visible = @$data / $rows;
    my $max_offset = @$data - $rows;
    my $units; 
    if ($_[0] eq 'scroll'){
        $units = $_[1];
        if ($_[2] ne 'units'){# page
            $units = $units * ($rows-3);
        }
    }
    elsif ($_[0] eq 'moveto'){
        $units = @$data *  $_[1] - $offset;
    }
    else{
        $units = $_[0];
    }
    $offset = int($offset + $units);
    if ($offset < 0){$offset = 0}
    elsif ($offset > $max_offset){$offset = $max_offset}
    for (0..$rows-1){
        my $row = $offset + $_;
        $entries->[$_]->configure(-textvariable => \$data->[$row]{value});
        $labels->[$_]->configure(-textvariable => \$data->[$row]{label});

    }
    $self->configure(-offset => $offset);
    my $first = $offset / @$data ;
    my $last  = ($offset + $rows) / @$data ;
    $sb->set($first, $last);
}