self.label = QtGui.QLabel(self)
self.label.sizePolicy = QtGui.QSizePolicy(QtGui.QSizePolicy.Expanding,
    QtGui.QSizePolicy.Expanding)
self.label.setSizePolicy(self.label.sizePolicy)
self.label.setMinimumSize(QtCore.QSize(450, 40))
self.label.setWordWrap(True)
self.verticalLayout = QtGui.QVBoxLayout(self)
self.verticalLayout.setSizeConstraint(QtGui.QLayout.SetFixedSize)
self.verticalLayout.addWidget(self.label)
resizing a dialog with PyQt4