# Create widgets.
mw = create_main_window
display = create_display(mw)

# open the file we monitor.
filehandle = open_file_for_monitoring('filename')

# set up monitor
mw->repeat( 1000, [monitor_file, filehandle, display ] )

# start main loop
MainLoop

sub monitor_file {
   new_text = <filehandle>
   display->insert('end', new_text)
   display->adjust_vertical_scroll
}

##</code><code>##

sub MainLoop {
   while (1) {
       my $next_event = Get_Next_Event_From_Queue();

       $next_event->execute;
   }
}