comment on

It's a common mistake in Tk, to use while loops, or sleep statements. These block the gui. Your main misunderstanding, is that you think that withdraw destroys a widget and all it contains. Withdraw just removes it from being mapped onto the screen, it still exists behind the scenes and can be running. The following code is a quick fix

#!/usr/bin/perl
use warnings;
use strict;
use Tk;

my $mw = tkinit;

my $tl = $mw->Toplevel(-title=>"Stupid Program");

my $text = $tl->Text()->pack();

my $flag = 0;

my $cancel_btn=  $tl->Button(-text=>"Cancel",
         -command=> sub { 
                 $flag = 1;          
               $tl->withdraw
   })->pack(-side =>'left', -expand=>1, -anchor => 'center');         
+         

my $do_btn=  $tl->Button(-text=>"Start",
        -command=> sub { 
                 while (<DATA>){
                        #     process data
                        #     output to a text widget
                        if($flag){last}
            $text->insert('end',"$_\n");
                        $text->update;
            $mw->after(1000);
                      }
         })->pack(-side =>'left', -expand=>1, -anchor => 'center');   
+               

MainLoop;

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You could also do it without a flag, using the ismapped method.

#!/usr/bin/perl
use warnings;
use strict;
use Tk;

my $mw = tkinit;

my $tl = $mw->Toplevel(-title=>"Stupid Program");

my $text = $tl->Text()->pack();

my $cancel_btn=  $tl->Button(-text=>"Cancel",
         -command=> sub { 
               $tl->withdraw
       })->pack(-side =>'left', -expand=>1, -anchor => 'center');     
+             

my $do_btn=  $tl->Button(-text=>"Start",
        -command=> sub { 
                 while (<DATA>){
                        #     process data
                        #     output to a text widget
                        if(! ismapped $tl){last}
            $text->insert('end',"$_\n");
                        $text->update;
            $mw->after(1000);
                      }
          })->pack(-side =>'left', -expand=>1, -anchor => 'center');  
+                

MainLoop;

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I'm not really a human, but I play one on earth. flash japh

In reply to Re: $widget->withdraw by zentara
in thread $widget->withdraw by Anonymous Monk

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