[gtkmm] Tooltips with gtkmm-2.3

[Chris Vine <chris cvine freeserve co uk>]

I have been trying out gtkmm-2.3.7, but I cannot work out how to get tooltips 
to show with Gtk::ToolButton objects placed in a Gtk::Toolbar.  The GTK+ 
equivalent GtkToolbar has a gtk_toolbar_append_item() function which has (as 
the third parameter) the tooltip text to be shown, but Gtk::Toolbar::append() 
does not appear to have anything equivalent to this.

As a hack I have also tried indirectly to get at a Gtk::Tooltips object by 
wrapping the output of Gtk::Toolbar::gobj->tooltips, and then calling 
Gtk::Tooltips::set_tip() on the individual toolbar buttons, but whilst this 
compiles it does not actually show any tips (even after calling 
Gtk::Toolbar::set_tooltips(true).

Am I missing something?

Chris.