That's what I would like to achieve:
But it turned out that way:
I found the cause of the problem because I called QWidget::setWindowFlags(Qt::FramelessWindowHint);This caused showMaximized() to show the wrong result.So I've reimplemented these two functions。
void MainWindowDef::showMax()
{
oldSize = this->size();
oldPoint = this->pos();
resize(QApplication::desktop()->availableGeometry().size());
move(0, 0);
isMax = true;
}
void MainWindowDef::showOld()
{
resize(oldSize);
move(oldPoint);
}