Getting "button-press-event" on a ToolButton

[Peter Daum <gator_ml yahoo de>]

Hi,

I am trying to create a context menu activated by the
right mouse button on a button in a toolbar,
doing something like

$button->signal_connect('button-press-event', sub {
  my $bt = $_[1]->button;
  $mnu->popup(undef,undef,undef,undef,$bt,0)if $bt == 3;};

With regular buttons, this works without a problem,
but I can't figure out any way how to receive the
button press events on the tool button.

I tried a bunch of different variations (like 
setting "add_events('button-press-mask')" on all
widgets, experiments with eventbox, ...).

Any ideas?
(I am using Perl, but the question should 
be language-independant)

Regards,
                Peter Daum