[PyQt] derive from a designer widget

[Mario Daniel Carugno]

Hi, i'm using pytq4 + designer4.
I want to design a generic main window with common buttons (next,
previous, new, edit, ...)
with a central area for data. That central area could be a frame.
But i want to design widgets to fill that frame independently. One
widget for products, other for
customers and so on.
I need then to 'mix' both widgets, or add the data widget into the
generic frame.
Damn it, i couldn't express it better >:-[
In QT3 remember i could derive my widget from another one made with
designer, but that is
not possible in QT4. That the behaviour i want.
I want to access the widgets in the parent (the generic main window)
and the widgets in the
inner area, as they belongs to the same object.

Sorry, english is not my tongue and this is hard to explain for me.
The idea is to design a generic main window that could be reused, and
just add a custom
widget in the middle of it, but integrating the widgets of both in the program.

Thanks