gVirtualx->AddWindow problem

ROOT
5

Try this, it works fine for me:

//______________________________________________________________________________
QRootCanvas::QRootCanvas(QWidget *parent) : QWidget(parent, 0), fCanvas(0)
{
   // QRootCanvas constructor.

   setAttribute(Qt::WA_PaintOnScreen, false);
   setAttribute(Qt::WA_OpaquePaintEvent, true);
   setAttribute(Qt::WA_NativeWindow, true);
   setMinimumSize(300, 200);
   setUpdatesEnabled(kFALSE);
   setMouseTracking(kTRUE);

   // register the QWidget in TVirtualX, giving its native window id
   int wid = gVirtualX->AddWindow((ULong_t)winId(), width(), height());
   // create the ROOT TCanvas, giving as argument the QWidget registered id
   fCanvas = new TCanvas("Root Canvas", width(), height(), wid);
   TQObject::Connect("TGPopupMenu", "PoppedDown()", "TCanvas", fCanvas, "Update()");
}

//______________________________________________________________________________
void QRootCanvas::resizeEvent( QResizeEvent *event )
{
   // Handle resize events.

   if (fCanvas) {
      fCanvas->SetCanvasSize(event->size().width(), event->size().height());
      fCanvas->Resize();
      fCanvas->Update();
   }
}