+ sign in merged cells (MSHFlexGrid)

Hi.

Im merging my data in a mshflexgrid.

Code:

---

'...
ListaResCen.FGLista.MergeCells = 2
ListaResCen.FGLista.MergeCol(0) = True
ListaResCen.FGLista.MergeCol(1) = True
ListaResCen.FGLista.MergeCol(2) = True
ListaResCen.FGLista.MergeCol(3) = True
ListaResCen.FGLista.MergeCol(4) = True
ListaResCen.FGLista.MergeCol(5) = True
ListaResCen.FGLista.MergeCol(6) = True
ListaResCen.FGLista.MergeCol(7) = True
ListaResCen.FGLista.MergeCol(8) = True
'...

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How can I add the + sign to collapse the merged rows? (or - sign to the inverse)
Thank you