Gtk2:Dialog->new

[Deling Ren <deling_ren 123mail org>]

Dear all,

I am trying to write an application whose main window is just a dialog. 
I tried to create the dialog using:

my $dialog = Gtk2::Dialog->new ('Hello world', $parent,
               ['destroy-with-parent','modal'],
               'gtk-ok', 'ok',
               'gtk-cancel', 'cancel');

I have no idea what value should I pass as $parent, since this dialog 
has no parent. Any suggestion will be highly appreciated. Thanks.

BTW, I have no background in GTK/GTK2/Perl, where shall I start to lean 
gtk2-perl? I didn't find any helpful tutotial to start off with. I have 
a lot of experience with MS Windows SDK/MFC though. Thanks!

Regards
Deling