Problems with 'signal_emit_by_name';

[Paul Schulz <pschulz foursticks com au>]

--------
Greetings,

[Disclaimer: I've just started using libgtk-perl so pleas bear with me.]
[System is current Debian/Potato]

I'm drawing on a pixmap, (the backing pixmap for a Drawing Area) in a
script copied from 'chart-demo.pl' example.

This is working very well except that I can't get the script to update
my changes to the screen.  If I resize the window, or move over it
then it gets a refresh event and displays correctly.

What is the correct thing to do here? Emit an expose signal for the
parts of the image that I've changed?

I get an error if I use 'signal_emil_by_name', and either I'm missing
something in the documentation, or it's wrong.

The tutorial suggests only a single parameter.. 
If I do this for the Drawing area widget, I get an error...
The following works, 

  $widget->signal_emit_by_name( 'expose_event', 'area' );

And passes the following parameters..

$VAR1 = [
          bless( {
                   '_gtk' => 136453616
                 }, 'Gtk::DrawingArea' ),
          undef
        ];

Normal expose events produce... how do I duplicate this?
(given $x1,$y1, $x2,$y2).

$VAR1 = [
          bless( {
                   '_gtk' => 136453616
                 }, 'Gtk::DrawingArea' ),
          bless( {
                   'window' => bless( {
                                        '_gtk' => 136455976
                                      }, 'Gtk::Gdk::Window' ),
                   'count' => '0',
                   'area' => [
                               573,
                               '0',
                               27,
                               100
                             ],
                   'type' => 'expose',
                   '_ptr' => 136521360
                 }, 'Gtk::Gdk::Event' )
        ];

Thanks in advence,
Paul
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