在构造函数中:setMouseTracking(true);
void LumiaMainwindow::mouseMoveEvent(QMouseEvent *mouseEvent)
{   
  if((mouseEvent->x()<(center->mask().boundingRect().bottomRight().x()+50))&&
      ((mouseEvent->x())>(center->mask().boundingRect().bottomRight().x())))
{
     mouseEvent->accept();
     setCursor(QCursor(Qt::SizeHorCursor));
}
else
{
  setCursor(QCursor(Qt::ArrowCursor));
}
  
QMainWindow::mouseMoveEvent(mouseEvent);
}