Created attachment 177189 [details]
Example that shows the bug.

Linux fortuna 2.6.37-11-generic #25-Ubuntu SMP Tue Dec 21 23:42:56 UTC 2010 x86_64 GNU/Linux
Python 2.7.1+
python-gobject 2.27.0-0ubuntu5
python-gtk2 2.22.0-0ubuntu1


First we need a class that contains some GTK+ widgets and a signal connected. I'll take this simple class:

class SomeWindow(object):

    def __init__(self):
        self.button = gtk.Button("Click me")
        self.button.connect("clicked", self._on_button_clicked)
        
        self.window = gtk.Window()
        self.window.add(self.button)

        print self.__dict__
    
    def show(self):
        self.window.show_all()
    
    def _on_button_clicked(self, *_):
        print self.__dict__

When I create and show the window with `SomeWindow().show()' the window is shown correctly but in the _on_button_clicked method __dict__ is {} (after the garbage collector has been invoked).

You'll find this example attached in the cycle_bug.py file.

There were some bugs like this in the past, especially
* http://www.daa.com.au/pipermail/pygtk/2008-August/015770.html and
* https://bugzilla.gnome.org/show_bug.cgi?id=92955
is very similar to this one.