QDockWidget *frame = new QDockWidget ;
QGridLayout *frameLayout = new QGridLayout(frame);
QWidget* child = new QWidget;
frameLayout->addWidget(child);
或者
QDockWidget *frame = new QDockWidget ;
QGridLayout *frameLayout = new QGridLayout;
QWidget* child = new QWidget;
frameLayout->addWidget(child);
frame->setLayout (frameLayout);