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);