#!/usr/bin/perl -w

use strict;
use Tk;

my $mw = tkinit;

my $notification = $mw->Toplevel();
$notification->geometry('+400+400');
$notification->overrideredirect(1);    # Remove window decorations
$notification->withdraw;               # Hide display window

$notification->Label(
    -text       => 'Your message displayed here.',
    -foreground => 'white',
    -background => 'black',
    -height     => 5
)->pack;

$notification->Button(
    -text    => 'Press Me',
    -command => sub {my $msg = $mw->messageBox(-icon => 'error', 
                       -message => "No tests selected", 
                       -title => 'Error', -type => 'Ok', 
                       -default => 'Ok');  
                     }

)->pack;
$mw->Button(
    -text    => 'Display Notification Window',
    -command => \&display_note
)->pack;

MainLoop;

sub display_note {
    $notification->deiconify;
    $notification->raise;
    
    # this is where you setup a condition to withdraw it
    $notification->after( 5000, \&hide_note );
}

sub hide_note {
    $notification->withdraw;
}