QT DLL的使用问题---QWidget: Must construct a QApplication before a QPaintDevice

    用Qt编写的dll有两个使用方式：

               1）启动启动一个Qt程序，程序自动会创建QApplication

               2)  不启动Qt桌面程序，直接调用dll。此时须new QApplication

                         static QApplication *g_application = NULL;
                          static int g_iApplicattion = 1;

                        if (g_application == NULL)
                         {
                                //g_application = new QApplication(g_iApplicattion,&g_pText);
                         }

                    注意：a）g_iApplicattion must stay valid for the entire lifetime of the QApplication object.,and must be greater than zero

                               b ) g_pText must contain at least one valid character string.