subclassing Gtk::CellRendererCombo

[Thomas Sailer <t sailer alumni ethz ch>]

I'm trying to subclass Gtk::CellRendererCombo. If I use
Gtk::CellRendererCombo, everything works. If I use
LblPlacementCellRenderer, displaying values works, but editing doesn't.
start_editing_vfunc always returns 0.

class LblPlacementCellRenderer : public Gtk::CellRendererCombo {
        public:
                LblPlacementCellRenderer(void);
};

LblPlacementCellRenderer::LblPlacementCellRenderer( void )
        : Glib::ObjectBase(typeid(LblPlacementCellRenderer)), Gtk::CellRendererCombo()
{
}

Subclassing Gtk::CellRendererText like this works for me.

I'm using an up-to-date Fedora Core 6:

$ rpm -q gtkmm24
gtkmm24-2.10.7-1.fc6

Does anyone know why this fails?

Thanks,
Tom