Using Qt classes in QtScript

[totem]

I'm trying to use Qt classes directly in QtScript

function Script ()
{
	var rect = new QRectF(0,0,10,5) ;
	var polygon = new QPolygonF(rect) ;
	level.addPolygon(polygon);
}
 
function entry_point()
{
	Script() ;
}

function Script ()
{
	var rect = new QRectF(0,0,10,5) ;
	var polygon = new QPolygonF(rect) ;
	level.addPolygon(polygon);
}

function entry_point()
{
	Script() ;
}

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When I evaluate the entry_point() function, this gives me :

ReferenceError: Can't find variable: QRectF

Does anybody can tell me what I'm missing (must be obvious) ?
If I can't use Qt this way, is there a solution ?