'Open the controlled widget (expand it to sizeHint).'

def open(self):

    self.__expanded = True
    self.__action.setChecked(True)
    if ((self.__splitter is None) or (self.__widget is None)):
        return
    hint = self.__widget.sizeHint()
    if (self.__splitter.orientation() == Qt.Vertical):
        end = hint.height()
    else:
        end = hint.width()
    self.__animation.setStartValue(0)
    self.__animation.setEndValue(end)
    self.__animation.start()
