Pyside problem

[appollosputnik]

I have a custom widget which is a chaco plot called
DefaultPlotWidget

I have inserted this widget in QGridLayout. Now I want to remove it from QGridLayout how can I type cast it to the actual widget.
[code]
widget = self.layout().itemAtPosition(row, self.columns).widget()
self.layout().removeWidget(widget)
[/code]
widget is QWidget not DefaultPlotWidget. How can I type cast it so that the DefaultPlotWidget gets removed..
Because the border of the DefaultPlotWidget is still there in the QGridLayout, QGridLayout is not updated.

Please help.