Gurus, How to prevent users from opening more than one "newWin" windows by clicking $button1 ? If there is an existing "newWin" opened, when user clicks button1, the existing window should be in focus instead of opening new window. Thanks. 
===========
use Tk;
use strict;

my $mw = MainWindow->new;
   my  $button1= $mw-> Button(-text=>"newWin", 
         -command=> 
   sub {
        my $top2 = $mw -> Toplevel(); 
        my $label1= $top2-> Label(-text=>'hi here')->pack(); 
    }
)->pack;


MainLoop;
================

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In reply to how to prevent more than 1 tk Toplevel windows from opening by henry888

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