How can to change the QGraphicsTextItem 's cursor width?

Hello ,
I am using a QGraphicsTextItem ,but the cursor in it is too thin to find it .
And I Find the QGraphicsTextItem doesn't supports the method of " setCursorWidth( ) ".

Does anybody know how to change it tell me please.
Thanks.

Code:

---

#include "cgTextItem.h"
#include <QPlainTextDocumentLayout>
 
 
cgTextItem::cgTextItem(QGraphicsItem *parent, QGraphicsScene *scene)
:QGraphicsTextItem(parent, scene)
{
	QFont newFont = font();
	newFont.setPointSize(24);
	setFont(newFont);
 
	setDefaultTextColor(Qt::blue);
 
	QPlainTextDocumentLayout *plainLayout = new QPlainTextDocumentLayout(document());
	plainLayout->setCursorWidth(100);
 
	document()->setDocumentLayout(plainLayout);
 
	setFlag(QGraphicsItem::ItemIsMovable,true);
	setFlag(QGraphicsItem::ItemIsSelectable,true);
	setTextInteractionFlags(Qt::TextEditorInteraction);
 
	setPlainText("New Item");
}

---

this is my construct function ,the QPlainTextDocumentLayout have a function setCursorWidth can be change the cursor width in the QGraphicsTextItem ,
but the effect is not good,it becomed very small. I don't know the reason .can you help me ?

And changed the setCursorWidth's value ,the effect is still .