if you're in Windows you may want toolbox attribute. Look:

use Tk;
$mw=tkinit;
$tl=$mw->Toplevel;
print hex($tl->id);
$tl->Button(-text=>'Ok')->pack;
#$tl->attributes(-toolwindow=>1);
$mw->after(1000,sub {$tl->attributes(-toolwindow=>1)});
MainLoop;
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