See Appendix C, "Answers," for the exercise answers.
9.5.1. What if the process of creating your window contents is a long job? Combine the QTimer method for long jobs with double-buffering to efficiently paint a complex scene without hanging the GUI. Your program's GUI should still respond to input while the application is painting the window. (You can easily check this by attempting to close the window while the program is painting.) See Appendix C, "Answers," for the exercise answers.