How to change Python Qt binding?

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In rqt's plugin tutorial in python, using qt_binding_helper is recommended/required for making plugin developers not to care which python - qt binding to use (namely either PyQt or PySide). But looks like qt_binding_helper internally uses PyQt by default. How can I change to PySide?

I tried following and still didn't work as I kind of expected.

from python_qt_binding.QtBindingHelper import select_qt_binding
:
class RealityWidget(QWidget):
    def __init__(self, context, node=None):        
        :
        select_qt_binding('pyside') # P.S.2
        loadUi(ui_file, self)

P.S.1 The reason I want to use PySide is first of all I like to avoid GPL that PyQt requires (as mentioned in python_qt_binding's wiki as well). Another trigger is that my code experiences this problem where using PyQt yields runtime error while PySide doesn't. This doesn't mean I have to use PySide but just want to avoid any possible unknown issues.

P.S.2 select_qt_binding

Update 9/17/12) As far as I searched my file system, no module uses python_qt_binding.QtBindingHelper.select_qt_binding.

__init__.py in rviz suggests that:

# Can use the following setattr() call to force one binding or the other.
# setattr(sys, 'SELECT_QT_BINDING', 'pyside')

But tyring to use like this it only fails to show still pyqt is in use:

import os
import sys
import rospy
import rosnode
setattr(sys, 'SELECT_QT_BINDING', 'pyside')        
from qt_gui.qt_binding_helper import loadUi
from python_qt_binding.QtBindingHelper import select_qt_binding, QT_BINDING 
from QtGui import QWidget, QTreeWidgetItem

class RealityWidget(QWidget):
    def __init__(self, context, node=None):
        select_qt_binding('pyside')
        print ('QT_BINDING=' + QT_BINDING) # this prints "pyqt"
        :
        ui_file = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'reality.ui')
        loadUi(ui_file, self)