a bunch of code, borrowed from pygtk, to add signals to a derived class. altered the histogramplot example to use a new signal.
a bunch of code, borrowed from pygtk, to add signals to a derived class.
altered the histogramplot example to use a new signal.

svn path=/trunk/; revision=156

potyl/perl-Gtk2,cpanxaoc/perl-Gtk2,cpanxaoc/perl-Gtk2,potyl/perl-Gtk2,cpanxaoc/perl-Gtk2,potyl/perl-Gtk2