Update after moving qgraphicstextitem

[IknowQT]

The graph was moved with the mouse, and the textitem was also moved according to the graph. The bottom textitem is cut off to the screen.
But what's strange is that when I click or switch to another screen, it works normally.

for (int i = 0; i < this->series().count(); i++)
	{
		usrLineSeries* pSeries = qobject_cast<usrLineSeries*>(this->series().at(i));

		if (pSeries)
		{
			foreach(auto item, pSeries->GetTextItems())
			{
				if (!bItemVisible)
				{
					item->setVisible(bItemVisible);
				}
				else
				{
					QPointF target(item->GetOriPos());
					QPointF p = this->mapToPosition(QPointF(target), pSeries);

					if (!this->plotArea().contains(p))	// 화면 벗어나면 visible 안함
						item->setVisible(false);
					else
					{
						QPointF sPos = this->mapToScene(p.x(), p.y());
						item->setPos(sPos.x(), sPos.y());
						item->setVisible(bItemVisible);
					}
				}
			}
		}
	}