Hmm.. I know how to destroy a window with a button and all but yeah I can't close it with that "X". Heres some of the relevant code which is really just a dialog box..

    my $dialog_comingsoon = $main_window->DialogBox( 
                -title   => "COMING SOON");
                    
            $dialog_comingsoon->Label(-text=>'Patience.')->pack;
            $dialog_comingsoon->Label(-text=>'This feature will be act
+            ive in the next release.')->pack; 
            $dialog_comingsoon->Label(-text=>'Thank You.')->pack;
[download]

Heres also an example picture of the dialog box:

http://www.angelfire.com/linux/penguinfood/dialogbox.jpg