new_contents: import sys
  from PyQt4 import QtGui
  from PyQt4 import QtCore
  
  
  
  def setStyleHelper(widget, style):
          widget.setStyle(style)
          widget.setPalette(style.standardPalette())
          for child in widget.children():
              if isinstance(child, QtGui.QWidget):
                  setStyleHelper(child, style)
  
  def change_style(widget, style):
      style=QtGui.QStyleFactory.create(style)
      if style: setStyleHelper(widget, style)
  
  
  
  class MainWindow(QtGui.QMainWindow):
      def __init__(self, parent = None):
          QtGui.QMainWindow.__init__(self, parent)
          self.setupActions()
          self.setupMenus()
          self.setupUi()
  
  
      def change_stylecleanlooks(self): change_style(app, 'cleanlooks')
      def change_styleplastique(self): change_style(app, 'plastique')
      def change_stylecde(self): change_style(app, 'cde')
      def change_stylemotif(self): change_style(app, 'motif')
      def change_stylewindowsvista(self): change_style(app, 'windowsvista')
  
  
      def setupActions(self):
  
          # scale mode
          self.scale_fitAction = QtGui.QAction(self.tr("Fit in view"), self)
          self.scale_scaleAction = QtGui.QAction(self.tr("Scale and crop"), self)
          self.scale_fitAction.setCheckable(True)
          self.scale_scaleAction.setCheckable(True)
  
          self.scaleGroup = QtGui.QActionGroup(self)
          self.scaleGroup.addAction(self.scale_fitAction)
          self.scaleGroup.addAction(self.scale_scaleAction)
          self.scale_fitAction.setChecked(True)
  
          # qt-styles
          self.style_plastiqueAction = QtGui.QAction(self.tr("Plastuique"), self)
          self.style_cleanlooksAction = QtGui.QAction(self.tr("Cleanlooks"), self)
          self.style_cdeAction = QtGui.QAction(self.tr("cde"), self)
          self.style_motifAction = QtGui.QAction(self.tr("motif"), self)
          self.style_windowsvistaAction = QtGui.QAction(self.tr("windowsvista"), self)
  
          self.style_plastiqueAction.setCheckable(True)
          self.style_cleanlooksAction.setCheckable(True)
          self.style_cdeAction.setCheckable(True)
          self.style_motifAction.setCheckable(True)
          self.style_windowsvistaAction.setCheckable(True)
  
          self.styleGroup = QtGui.QActionGroup(self)
          self.styleGroup.addAction(self.style_plastiqueAction)
          self.styleGroup.addAction(self.style_cleanlooksAction)
          self.styleGroup.addAction(self.style_cdeAction)
          self.styleGroup.addAction(self.style_motifAction)
          self.styleGroup.addAction(self.style_windowsvistaAction)
          self.style_cleanlooksAction.setChecked(True)
          self.style_plastiqueAction.setChecked(True)
          self.style_cdeAction.setChecked(True)
          self.style_motifAction.setChecked(True)
          self.style_windowsvistaAction.setChecked(True)
  
          # style conns
          self.connect(self.style_plastiqueAction, QtCore.SIGNAL('triggered()'), self.change_styleplastique)
          self.connect(self.style_cleanlooksAction, QtCore.SIGNAL('triggered()'), self.change_stylecleanlooks)
          self.connect(self.style_cdeAction, QtCore.SIGNAL('triggered()'), self.change_stylecde)
          self.connect(self.style_motifAction, QtCore.SIGNAL('triggered()'), self.change_stylemotif)
          self.connect(self.style_windowsvistaAction, QtCore.SIGNAL('triggered()'), self.change_stylewindowsvista)
  
  
      def setupMenus(self):
          styleMenu = self.menuBar().addMenu(self.tr("Style"))
          styleMenu.addAction(self.style_cleanlooksAction)
          styleMenu.addAction(self.style_plastiqueAction)
          styleMenu.addAction(self.style_cdeAction)
          styleMenu.addAction(self.style_motifAction)
          styleMenu.addAction(self.style_windowsvistaAction)
  
      def setupUi(self):
          bar = QtGui.QToolBar()
          mainLayout = QtGui.QVBoxLayout()
          widget = QtGui.QWidget()
          widget.setLayout(mainLayout)
          self.setCentralWidget(widget)
          self.setWindowTitle("styler")
  
  
  if __name__ == '__main__':
      app = QtGui.QApplication.instance()
      if not app:
          app = QtGui.QApplication([])
      change_style(app, "cleanlooks")
      window = MainWindow()
      window.show()
      app.exec_()
  
subject: Create Style-Chooser.py