in reply to bind up and down keys in a tk listbox

If you want the up/down keys to control the listbox then I think you need to manage the focus. Adding an explict call in your code as follows enables these keys.
foreach my $key ("a" , "b" , "c") { $lb -> insert( 'end', $key ); } $lb->activate ( 0 ) ; $lb->selectionSet ( 0 ) ; $lb->focus();
I'm _far_ from being a Tk expert, so I'd advise you to check out Tk::Focus docs for yourself.
my name's not Keith, and I'm not reasonable.