How to force emit of signal attached to built-in widget?

[Toralf Lund <toralf procaptura com>]

Is there any way I cat force an "emit" on the signals of the normal 
Gtkmm widgets? I mean the signals returned via the signal_<something>() 
methods? I want to be able to do something like

myButtonWidget.signal_clicked().emit()

(but with other signals, too), only I can't, because the "signal" method 
returns a Glib SignalProxy (and not a SigC signal), which doesn't have 
an emit(), as far as I can tell.

- Toralf