Your foreach loop will only make your GUI widget print the last element in the array when you select an entry, you need to re-engineer that. You're not making use of the widget state variable $exportngram whose value toggles between 0 and 1 depending on whether it is unselected or selected but again, this might not be serving any purpose in the code snippet you posted.

I suggest you re-implement the same using a ListBox or a BrowsEntry widget..

#This snippet uses a listbox to deliver the required behavior.
#You can double click a value to show or just use the print button.
use strict;
use warnings;
use Tk;
my $mainWindow = MainWindow->new(-title=>"Main Window");
my $listBox = $mainWindow->Scrolled(
   'Listbox',
   -scrollbars=>'e'
   )->pack;
$listBox->insert('end',qw(Nickle Dime Quarter));

$listBox->bind('<Double-1>', \&getActive);
$mainWindow->Button(
                    -text=>'print value',
                    -command=>\&getActive,
                    )->pack();

sub getActive{
    my $currency;
    $currency = $listBox->get('active'); #get the current selection
    print  $currency,"\n";
    };

MainLoop;
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