How to draw QGraphicsItem at the same location?

[jeanremi]

H'llo there,

I'm trying to paint a QGraphicsItem to stay at the top edge of my view, but when I scroll the view down, the item scrolls off the view.
I have connected the vertical scroll bar valueChanged() function to call my slot:

// vertical_scroll is the slot that gets called
        // ival comes from valueChanged(int)
	void my_graphics_item::vertical_scroll(int ival)
		{			
			int top = pgraphicsview->viewport()->rect().top();
			this->moveBy(0, top);
			this->update();
		}

// vertical_scroll is the slot that gets called
        // ival comes from valueChanged(int)
	void my_graphics_item::vertical_scroll(int ival)
		{			
			int top = pgraphicsview->viewport()->rect().top();
			this->moveBy(0, top);
			this->update();
		}

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1/ when this slot is called, why is top always 0? (the view is scrolled down, but this is always returned as 0)
2/ when I use ival instead of top, item moves down in big steps.
3/ how do I solve this issue? What am I doing wrong?

I just want the item to stay in view regardless of my scrolls (top, right, left or bottom).

Many thanks
Jean