from PySide import QtCore, QtGui
from PySide.QtUiTools import QUiLoader

from PySide.QtGui import QGraphicsView

class CustomWidget(QGraphicsView):
    pass

class MyQUiLoader(QUiLoader):
    def __init__(self):
        QUiLoader.__init__(self)
        self.registerCustomWidget(CustomWidget)

    def createWidget(self, className, parent=None, name=""):
        print('Creating %s' % className)
        widget = QUiLoader.createWidget(self, className, parent, name)
        print('Created %s' % className)
        return widget

if __name__ == "__main__":
    app = QtGui.QApplication([])

    ui = MyQUiLoader().load('bug.ui')