Some attempts: 1) Inserted the line

$text->delete('0.0', 'end');
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anywhere possible. 2) Deleted all references to "privateData". 3) Added, removed and changed:

$mw->withdraw;

$mw->protocol(WM_DELETE_WINDOW => [ $mw => 'withdraw']);

$mw->Advertise('text' => $text);

$mw->Redirect(1);

$mw->destroy;

$mw->OnDestroy([ 'DecrementReferenceCount' => $error_window ]);
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My current suspicion is that something could be added or changed in the following line of the Populate subroutine:

$mw->protocol(WM_DELETE_WINDOW => [ $mw => 'withdraw']);
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but I don't know what.