@MyMainWindow(){
MyWidget * wdgt = new MyWidget(this);
connect(wdgt, SIGNAL(mySignal()), this, SLOT(onComeSignal()));
}
class MyWidget : public QWidget{ Q_OBJECT
public: MyWidget(QWidget * parent): QWidget(parent){
QPushButton * btn = new QPushButton(this);
connect(btn, SIGNAL(clicked (bool), this, SLOT(onClick(bool)));
}
private slots: onClick(bool){emit mySignal();}
signals: void mySignal();
}@