发送按键事件到当前聚焦的窗体。
QWidget *receiver = QApplication::focusWidget();
qDebug()<<"Send key event to focus widget "<<receiver->objectName();
QKeyEvent keyPress(QEvent::KeyPress, key, Qt::NoModifier, value);
QKeyEvent keyRelease(QEvent::KeyRelease, key, Qt::NoModifier, value);
QApplication::sendEvent(receiver, &keyPress);
QApplication::sendEvent(receiver, &keyRelease);