I finally figured what I was missing. I forgot to import my Widget
class!!! I have imported Tkinter in the module for other GUI related
stuff. So Python was testing my Button class against Tkinter's Widget
class, and that's why the result was False. It finally made sense :)
Thank you Anand and
>Then I have an instance of class Button called obj. My probelm is that
>the test isinstance(obj, Widget) resturns False!
>
You must have a typo somewhere. Please try this little test program.
>>> class Widget(object):
... pass
...
>>> class Button(Widget):
... pass
...
>>> b = B
