The error message tells it: You must create a QApplication before you can create the form. Basically, formm() from your first script contains everything you must do:
- Create a QApplication object
- Create the widgets to show
- Enter the event loop via QApplication::exec()
In the context of your second script, this would read like:
import Form2use4ques4stackoverflow_2013_02_23_am_09_33_45_
app = QApplication(sys.argv)
nuform = Form2use4ques4stackoverflow_2013_02_23_am_09_33_45_.Form()
nuform.prefix_label.setText('newtext')
nuform.show()
return app.exec()