Hi, I have the following code: 
use strict;
use warnings;
use Tk;
use Tk::DialogBox;


my $mw = MainWindow->new();
$mw->OnDestroy(\&exit_app);

$mw->Button(-text => 'Exit', -command=> sub {$mw->destroy})->pack(-sid
+e=>'right', -ipadx => 10, -padx=>30);


MainLoop;

sub exit_app{
    print "1";
        my $db = $mw->DialogBox(-title => 'Error',-buttons => ['CSV','
+Abandon']);
        $db->Label(-text => "Do you wish to save a new CSV file or aba
+ndon changes?")->pack();
        my $button = $db->Show();
    if ($button eq 'CSV'){
        save_csv();
        }
}

sub save_csv{
    return 1;
}

[download]
When I exit (either using the button or using the X in the top right) I get a 1 printed but no dialog box. The documentation for OnDestroy says
OnDestroy accepts a standard perl/Tk callback. When the window associated with $widget is destroyed then the callback is invoked. Unlike $widget->('<Destroy>',...) the widgets methods are still available when callback is executed, so (for example) a Text widget can save its contents to a file.
This doesn't seem to be the case here, the DialogBox is not created. I am aware that I could remove $mw->OnDestroy() and call exit_app() directly from the button and then do $mw->destroy() at the end of the sub. However I then need to be able to disable (or preferably trap) the use of the X button. Any ideas?

In reply to $mw->OnDestroy and Dialog Box by Graham Drabble

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