#!/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;
}