QMainWindow && QToolBox

[eleanor]

Hi, I have a problem: I have a main window where I add centralWidget().
The class inherits QMainWindow.

QToolBox *m_pToolbox = new QToolBox();
              QTabWidget *m_pTabVnos = new QTabWidget();
              m_pToolbox->addItem(m_pTabVnos,trUtf8("Insert));
	setCentralWidget(m_pToolbox);

QToolBox *m_pToolbox = new QToolBox();
              QTabWidget *m_pTabVnos = new QTabWidget();
              m_pToolbox->addItem(m_pTabVnos,trUtf8("Insert));
	setCentralWidget(m_pToolbox);

To copy to clipboard, switch view to plain text mode 

Now I want this widget not to resize itself through all the central widget.
I want this QToolBox to be 1/3 of the width of the central widget (like in kpdf program).
The rest of the space (so 2/3 of the width) will be empty or now.

How can I do that?