Dynamic Drawing of BSpline Curve

I do it by maintaining a dynamic list, for the coordinates, that can grow as the user clicks the screen and then create a TColgp_SequenceOfPnt and append all the points in the list. Then I use a TColgp_Array1OfPnt with range 1,nbPoints and copy points from the sequence to it and then send it to GeomAPI_PointsToBSpline. My application has an interactive dialog with a multicolumn list box that keeps track of all the points clicked/selected by the user. The list cells are editable and the user may enter coordinates manually. While the user is entering or adding points, it is stored in the dynamic list. Every event of entering the coordinate or a click on the screen or a selection of existing point forces a refresh on the curve building routine in a local AIS context. Once the user commits the Apply/Ok button on the dialog the final curve is built and displayed after closing the local contexts.