I'm not going to write simple popup code for you. To do it correctly would take a few hours. There are alot of free examples on the net. I will however, give you a few tips on HList.

First, when you make a selection, it gets the entire multicolumn row. So when you make your popup dialog for new text, you need to remember, or housekeep, which column you are changing. For example, suppose you had 3 columns, you would need something like

my $newtext0 = 'foobar0';  #get from a popup dialog or wherever
my $newtext1 = 'foobar1';
my $newtext2 = 'foobar2';

$hlist->selectionSet($s);

$hlist->itemConfigure($s, 0,  -text=> $newtext0 ); #column 0
$hlist->itemConfigure($s, 1,  -text=> $newtext1 ); #column 1
$hlist->itemConfigure($s, 2,  -text=> $newtext2 ); #column 2
[download]

If you want a free HList program to look at, see ztkdb-sql or ztkdb