QVBoxLayout problem in Ubuntu 10.04 LTS 32bit

Well, can someone explain me this situation: On Windows, my code works well, on Linux Ubuntu 10.04 LTS Desktop Edition, when I run my app, the app's Main Windows contains some central widget, which to QVBoxLayout is applied (via QWidget::setLayout). Now, once I add QGroupBox with bunch of controls in it, the central widget's layout seems not to work, because QGroupBox is set in upper left corner and no controls inside QGroupBox are visible, since the QGroupBox is not shown properly. I attached screenshot. WHat could be wrong?http://www.qtcentre.org/attachment.p...256337&thumb=1