Hi!

You were close, but you forgot -row:

use Tk;

my $top = new MainWindow();
my %density = (A=>1,B=>2,C=>3);
my $row = 0;
foreach (sort keys(%density)) {
    my $keytext = $top->Label(
        -height=>1,-width=>10,-text=>$_,-justify=>'left')->grid(-row=>
+$row,-column=>0);
    my $denbox = $top->Entry(
        -textvariable=>\$density{$_},-width=>5)->grid(-row=>$row,-colu
+mn=>1);
    $row++;
}

MainLoop();
[download]

mawe