通过屏幕截图实验，了解图形桌面的应用， 定时器的使用方法， 与Qpixmap 类的使用方法。针对前面学习的标准对话框的使用复习。-By screenshot experiments to understand graphical desktop applications to use the timer, and Qpixmap class is used. Standards of learning in front of the dialog box for the use of revie