[4.4.0] QDockWidget visibilityChanged(bool) / isVisible() bug

Run the code below and click alternatively on Dock 1 and Dock2.
The results of the visibilityChanged(bool) signal and isVisible() do not match.

//--------------------------------------------
#include <QtGui>

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
MainWindow() : QMainWindow()

{ QTextEdit * textEdit = new QTextEdit; textEdit->insertPlainText( "Hello World" ); setCentralWidget( textEdit ); dock1 = new QDockWidget( this ); dock1->setWidget( new QTextEdit( dock1 ) ); dock1->setWindowTitle( "Dock 1" ); addDockWidget( Qt::RightDockWidgetArea, dock1 ); dock2 = new QDockWidget( this ); dock2->setWidget( new QTextEdit( dock2 ) ); dock2->setWindowTitle( "Dock 2" ); tabifyDockWidget( dock1, dock2 ); QObject::connect( dock1, SIGNAL( visibilityChanged( bool ) ), this, SLOT( printDock1( bool ) ) ); QObject::connect( dock2, SIGNAL( visibilityChanged( bool ) ), this, SLOT( printDock2( bool ) ) ); }

public slots:
void printDock1( bool b )
{
if ( b )

{ if ( dock1->isVisible() ) qDebug( "dock1 is visible" ); else qDebug( "dock1 is visible, but isVisible() contradicts" ); }

else

{ if ( ! dock1->isVisible() ) qDebug( "dock1 is invisible" ); else qDebug( "dock1 is invisible, but isVisible() contradicts" ); }

qDebug();
}

void printDock2( bool b )
{
if ( b )

{ if ( dock1->isVisible() ) qDebug( "dock2 is visible" ); else qDebug( "dock2 is visible, but isVisible() contradicts" ); }

else

{ if ( ! dock1->isVisible() ) qDebug( "dock2 is invisible" ); else qDebug( "dock2 is invisible, but isVisible() contradicts" ); }

qDebug();
}

private:
QDockWidget * dock1;
QDockWidget * dock2;
};

int main( int argc, char * argv[] )
{
QApplication app( argc, argv );
MainWindow mainWindow;
mainWindow.show();
return app.exec();
}

#include "main.moc"
//--------------------------------------------