Strange bug while subclassing Gtk2::Box

[Jaap Karssenberg <j g karssenberg student utwente nl>]

Hi,

For zim I'm working on a Gtk2::Ex::PathBar class to implement a path bar 
that looks like the one that is found in the gtk filechooser. Now I have 
a strange bug. My implementation works perfectly fine on my own system 
which runs archlinux. But I now get bug reports from people with gentoo 
and slackware systems that my widget doesn't render properly. I tried 
comparing the versions for both gtk+ and gtk2-perl running on those 
systems, as well as compile time options but I didn't find anything 
except for the fact that it works on one distro but not on the other.

The problem is this: my widget is a subclass of Gtk2::Box which 
implements size_request and size_allocate. Now on some systems it justs 
works, on other systems it doesn't. When it doesn't the buttons are 
allocated but they don't show up in the widget. But they are there, they 
are clickable - they just don't show.

The code below reproduces the problem. If you do see the buttons that 
means you have one of the systems where it just works, if you see an 
empty space try clicking it, you should see output from the buttons 
being clicked in your terminal.

I really hope someone can tell me how to fix this.

-- Jaap <pardus cpan>





#!/usr/bin/perl

package MyBox;

use strict;
use Gtk2;
use Glib::Object::Subclass
        Gtk2::Box::,
        signals => {
                size_request => \&do_size_request,
                size_allocate => \&do_size_allocate,
        };

sub do_size_request {
        # get minimum required size and store it in $requisition
        my ($self, $requisition) = @_;
        my ($height, $width) = (0, 0);
        for ($self->get_children) {
                my $req = $_->size_request;
                my ($w, $h) = ($req->width, $req->height);
                $height = $h if $h > $height;
                $width += $w;
        }
        $requisition->height($height);
        $requisition->width($width);
}

sub do_size_allocate {
        # distribute given space to children
        my ($self, $allocation) = @_;
        my ($x, $y, $w, $h) = ($allocation->values);
        my $all = Gtk2::Gdk::Rectangle->new($x, $y, 0, $h); # x, y, w, h
        for ($self->get_children) {
                my $req = $_->size_request;
                my $req_w = $req->width;
                $all->width($req_w);
                $_->set_child_visible(1);
                $_->size_allocate($all);
                $all->x( $all->x + $req_w );
        }
}

package main;

use strict;
use Gtk2 '-init';

my $window = Gtk2::Window->new('toplevel');
$window->signal_connect(destroy => sub { Gtk2->main_quit });
my $box = MyBox->new;
$window->add($box);

for my $i (1 .. 5) {
        my $button = Gtk2::Button->new("Button $i");
        $button->signal_connect(
                clicked => sub {print "You clicked button $i\n"} );
        $box->add($button);
}

$window->show_all;

Gtk2->main;

exit 0;