Gtk::CellRendererAccel does not emit accel-edited signal
I can't implement any signal handler/callback that reacts to this signal/event.
In this case
on_accel_edited is never called.
g_signal_connect(renderer_accel.gobj(), "accel-edited", G_CALLBACK(another_on_accel_edited), &on_accel_edited);
In this case, the C-version
another_on_accel_edited is called. (But I don't know how to indirectly call my slot
on_accel_edited from there.