gtkmm 3.4.0 - Gtk::Switch where is the signal "activate"?

[Giuseppe Penone <giuspen gmail com>]

Hi,
I would like to use the signal "activate" of the widget Gtk::Switch (which I discovered through glade signals tab),
I see that it exists in gtk 3.2: http://developer.gnome.org/gtk3/3.2/GtkSwitch.html#GtkSwitch-activate
but it is not mentioned on http://developer.gnome.org/gtkmm/stable/classGtk_1_1Switch.html
and the "m_switch.signal_activate()" causes error at compilation time.
Cheers,
Giuseppe.