Gtk.notebook#append_page and Gtk.frame's ?packing: type mismatch?

Hi there,

I've been playing with lablgtk2 recently, following the tutorial [1], and it
looks like it's either old or buggy (leaving aside some whitespace issues),
and cannot be compiled as is.

GBin.frame's ?packing type is "GObj.widget -> unit", but in this example it
then calls notebook#append_page which returns int (GObj.widget -> int), and
thus leading to a type mismatch error.  It's not hard to work around, but it
still looks like a bug to me: could it be that append_page started to return
int, but no one revisited places where it was also used for ?packing?

./danfe

[1] http://plus.kaist.ac.kr/~shoh/ocaml/lablgtk2/lablgtk2-tutorial/x1684.html