QToolBar isn't dockable on Zaurus

[simonqu]

I'm developing an application for sharp zaurus 5600 and encontered a QToolBar related problem. The program is working fine in my PC. When tranfered to PDA, the QToolBar isn't dockable. Any body here can help me?
Thanks
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Here enclosed the program
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#include <qapplication.h>
#include <qtoolbar.h>
#include <qwhatsthis.h>

class SmMainWin_QT:pulic QMainWindow
{
  public:
          SmMainWin_QT();
}
SmMainWin_QT::SmMainWin_QT():QMainWindow(0, "test")
{
  resize(235, 315);
  QToolBar * tool_bar = newQToolBar(this);
  addToolBar(tool_bar, Minimized);
  (void)QWhatsThis::WhatsThisButton(tool_bar);
}

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