Display dynamic (changing) graphics

Hello,

I have to display 3d points that are generated dynamically (anytime some input device is moved).
So I've created a class inheriting AIS_InteractiveObject and redefined Compute(Handle_PrsMgr_PresentationManager3d, Handle_Prs3d_Presentation, ...) method.

This sub-class relies on a Graphic3d_ArrayOfPrimitives being filled with specific purpose addPoint() :

class AIS_Path : public AIS_InteractiveObject
{
public:
AIS_Path(Standard_Integer maxPoints)
: m_points(new Graphic3d_ArrayOfPolylines(maxPoints))
{
}

void addPoint(const gp_Pnt& pnt)
{
m_points->AddVertex(pnt);
}

protected:
void Compute(const Handle_PrsMgr_PresentationManager3d& pm,
const Handle_Prs3d_Presentation& pres,
const Standard_Integer mode)
{
Handle_Graphic3d_Group group = Prs3d_Root::CurrentGroup(pres);
if (group.IsNull())
return;

group->BeginPrimitives();
group->AddPrimitiveArray(m_points);
group->EndPrimitives();
}

void ComputeSelection(const Handle_SelectMgr_Selection& selection, const Standard_Integer mode)
{ }

private:
Handle_Graphic3d_ArrayOfPrimitives m_points;
};

Each time a new point is added AIS_InteractiveContext::RecomputePrsOnly() is called and then Update() but only the points added with addPoint() before the very first call to Display() can be seen, after that nothing is displayed.

How should I proceed to get things work ?