Hiding and showing a QMainWindow results in resize

The steps to reproduce this are:

QMainWindow::hide();
use mouse to resize the window
QMainWindow::show();

this will cause the window to shirnk, because adjustSize() is called in QWidget::setVisible() if Qt::WA_Resized is false.

The following code reproduces this behaviour:

Use QWidget instead of QMainWindow or uncomment the setAttribute() to stop the shrining.

#include <QtGui>
#include <QDebug>

class MainWidget : public QWidget
{
Q_OBJECT

public slots:
void showHide()
{
if (showHideWidget->isVisible())
showHideWidget->hide();
else

{ qDebug() << showHideWidget->testAttribute(Qt::WA_Resized); // showHideWidget->setAttribute(Qt::WA_Resized); showHideWidget->show(); }

}

public:
MainWidget(QWidget *parent = 0) : QWidget(parent)

{ showHideButton = new QPushButton("Show-Hide"); showHideWidget = new QMainWindow; QHBoxLayout *layout = new QHBoxLayout; layout->addWidget(showHideButton); setLayout(layout); connect(showHideButton, SIGNAL(clicked()), this, SLOT(showHide())); }

private:
QPushButton *showHideButton;
QWidget *showHideWidget;
};

#include "main.moc"

int main(int argc, char **argv)
{
QApplication app(argc, argv);
MainWidget *main = new MainWidget;
main->show();
return app.exec();
}