GtkCellLayout::set_cell_data_func issue in Gtk2

I just upgraded from the Beta to php-gtk 2. I've been tweaking things to 
work with it (mainly the Gtk::TYPE's to GObject::TYPE) but I've run 
across one issue with GtkCellLayout::set_cell_data_func.

Before, I could pass it a callback function in the current class like so:

$col->set_cell_data_func($renderer, array($this, 'format_col'));

And that worked fine.. now it seems it won't take the array and returns 
an error:

Warning: Unable to invoke callback 'Array' specified in File.php on line xxx

Has this changed any in the new release?

Thanks!

-Matt