Vertical Scrollbar Disappears

[Budman <budman intergrafix net>]

This is one of my first attempts at writing a GTK app.  I have the code
accessing a directory list, and updating List widgets inside of
ScrolledWindow widgets.  Everything was working fine until I selected a
directory that contained a lot of files, approximatelly 2,200 files. 
These were all added to the listbox, which after adding items to the
listbox, the vertical scrollbar would disappear leaving the list of
2,200 files useless with a scrollbar.  When I selected another directory
with much lesser files, the vertical bar came back.

Is there a buffer size that needs adjusting?  Or a limit setting that
allows huge amounts of list items.

$file_scrolled_window = new Gtk::ScrolledWindow( undef, undef );
$table->attach_defaults($file_scrolled_window, 1, 2, 2, 3 );
$file_scrolled_window->set_policy( 'automatic', 'automatic' );
$file_scrolled_window->show();
$file_list = new Gtk::CList( 1 );
$file_scrolled_window->add_with_viewport( $file_list );
$file_list->set_selection_mode( 'multiple' );
$file_list->set_shadow_type( 'none' );
$file_list->show();

I'm using GTK-1.2.8.
Thanks for any help.
Rich