nanogui: Thread: Query: can u create a widget as a child of window?

        I would like to know whether u can create a widget as a child of
a window created  using GrNewWindow(). I tried this, but it was not
working. Is it possible to have a heirarchy like this :

1) root window
2) child widgets(containers) -children of root window
3) specialized widgets- children of a container widget

Thanks in advance!!
Bipin