G'day ngocanh,

Welcome to the Monastery.

This has been discussed before. Take a look at:

• perl tk listbox how to return choice to main program
• Returning a value from a Perl Listbox

Yes I am aware, I actually learnt how to create the GUI from these posts. That is why I do not understand my program hangs after the button click.

The referenced threads do appear to accomplish what you ask for. However, I consider it a bad idea to mix GUI with command-line interface in the same script. It may confuse your users more than help them. The somewhat non-standard code will be a maintenance problem for the life of your script.
Bill

Thanks! This solved my problem. I realised I was having another mainwindow open. Even though the 2 windows do not seem to be related, destroying the other window helped my to proceed with my script flow :)

Hello ngocanh,

I'm not sure what you want to see, so below is the code for the whole subroutine I'm writing

The whole reason I have this subroutine is for user to select some items in the @newSeqUnique array and return the selected array to the calling function

Currently the code is stuck at the MainLoop; statement

 
sub getSelectedSeq {
    my $newSeqUniqueRef = shift; my $grp = shift;
    my @newSeqUnique = @$newSeqUniqueRef;
    my @newSeqUniqueSorted = sort{$a->{ID} cmp $b->{ID} ||
                    $a->{folder} cmp $b->{folder}} @newSeqUnique;
    my @displayedArr; my $displayedStr;
    my @selectedArr;
    foreach (@newSeqUniqueSorted) {
        $displayedStr = $_->{ID}." - ".$_->{folder};
        push (@displayedArr, $displayedStr);
    }
    select STDOUT;
    foreach (@displayedArr) {
        print "$_\n";
    }

#    my $mw = MainWindow->new(-title=>"Select sequences");
    my $mw = new MainWindow;
    
    $mw->Label(-text => "Below is a list of sequences not found in exi
+sting group $grp table")->pack();
    $mw->Label(-text => "Please select sequences to be added to new ta
+ble")->pack();
    
    my $lb = $mw->Scrolled("Listbox",
               -scrollbars => "osoe",
               -height =>10,
               -width => 30,
               -selectmode => "extended");

        my $real_lb = $lb->Subwidget('scrolled');
        $real_lb->configure(-borderwidth=>2);
    $lb->insert("end", @displayedArr);
    $lb->pack(-fill=>"both");
    $mw->Button(-text => "Select",
                     -command => sub{@selectedArr=$lb->curselection;$m
+w->destroy();})->pack();
    $lb->selectionSet('end');
    $lb->see('end');
    MainLoop();

    foreach (@selectedArr) {
                print "$_\n";
        }
        
    my @arr; my @temp; my ($index, $ID, $folder, $obj);
    if ((@selectedArr)&&(defined $selectedArr[0])) {
        foreach (@selectedArr) {
            push (@arr, $newSeqUniqueSorted[$_]);
        }
    }else {
        @arr = ();
    }
    
    return \@arr;
}
[download]

I can't replicate your problem. I added use Tk; to the top of the script, and the following to the bottom:

print %{ getSelectedSeq([{ ID     => 1,
                           folder => '/'
                         },
                         { ID     => 2,
                           folder => 'home'
                         }], 12)->[0] };
[download]

I'm getting the output and the program terminates.

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]

#!/usr/bin/perl --
use strict; 
use warnings;
use Tk qw/ tkinit /;
my $mw = tkinit;
my $done;
my $bu = $mw->Button( 
    -text => "clickme", 
    -command => sub { $done = "I am done " . gmtime; } ,
)->pack;
for( 1 .. 3){
#     $mw->deiconify;
#     $mw->raise;
    $mw->Popup;
    $bu->focus;
    $mw->waitVariable(\$done);  ## like mainloop until $done changes
    print "I am $done again\n";
    $mw->withdraw; ## hide, no more mainloop
    sleep 1;
}
[download]