Gtk-perl: custom cell renderer?

["Xi Yang" <jiandingzhe 163 com>]

Hi everyone! I'm trying to create my customized cell renderer, but occurred some problems.


I'm making the app using Perl. The renderer subclass looks like this: some attribute definitions, and a 
trival render function:


################################################
package Gdraw2Gtk::CellRenderer::PlainColor;


use common::sense;
use Gtk2;
use Glib::Object::Subclass(
'Gtk2::CellRenderer',
properties => [
Glib::ParamSpec->long(
'red', '', '', 0, 1, 0, [qw/readable writable/]
),
Glib::ParamSpec->long(
'green', '', '', 0, 1, 0, [qw/readable writable/]
),
Glib::ParamSpec->long(
'blue', '', '', 0, 1, 0, [qw/readable writable/]
),
Glib::ParamSpec->long(
'alpha', '', '', 0, 1, 0, [qw/readable writable/]
),
]
);


sub render {
    say "on render: @_";
}


1;
################################################


It was binded to a column while building the GUI:


################################################
    my $col_stroke = $builder->get_object('PageTree_StrokeColorCol');
    my $r_stroke = Gdraw2Gtk::CellRenderer::PlainColor->new;
    $col_stroke->pack_start( $r_stroke, TRUE );
    $col_stroke->add_attribute( $r_stroke, 'red'   => COL_STROKE_R );
    $col_stroke->add_attribute( $r_stroke, 'green' => COL_STROKE_G );
    $col_stroke->add_attribute( $r_stroke, 'blue'  => COL_STROKE_B );
    $col_stroke->add_attribute( $r_stroke, 'alpha' => COL_STROKE_A );
################################################


While running, I created, this error message is shown, and the program exits immediately:
GET_SIZE must return four values -- the x_offset, y_offset, width, and height at 
/usr/local/share/perl5/Gdraw2Gtk/App.pm line 895.


I never explicitly called GET_SIZE. Line 895 was the call to Gtk2->main(). So what is the problem?


Thanks!!