use Tk::DialogBox;
use Tk::JPEG;
[.....]
$d = $mw->DialogBox( -title => "reboot", -buttons => [ qw/Yes Cancel/]);
$mw->Photo( "redx", -format => "JPEG", -file => "redx.jpg");
$d->add( Label, image => "redx");
$d->add( Label, -text => "Please reboot now?");
if( $d->Show eq "Yes") {
     halt();
}