如何在pygtk中创建新信号

import pygtk
pygtk.require('2.0')
import gtk
import gobject

class CustomButton(gtk.Button):
    __gsignals__ = {
        'custom-clicked': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE, ())
    }

    def __init__(self, *args, **kwargs):
        super(CustomButton, self).__init__(*args, **kwargs)
        self.connect('clicked', self.on_clicked)

    def on_clicked(self, widget):
        self.emit('custom-clicked')

def main():
    window = gtk.Window(gtk.WINDOW_TOPLEVEL)
    window.set_title('Custom Signal Example')
    window.connect('destroy', lambda w: gtk.main_quit())

    button = CustomButton('Click me')
    button.connect('custom-clicked', on_custom_clicked)
    window.add(button)

    window.show_all()

def on_custom_clicked(widget):
    print('Custom clicked signal received')

if __name__ == '__main__':
    gtk.main()