Hi,

ControlPoints help topic says that Bézier links have four control points per segment, and you should really stick to that or will get index exceptions later on. If you need to show Bezier link as a straight line initially, insert two control points between the end ones at (dx* 1/3, dy * 1/3) and (dx * 2/3, dy * 2/3) offsets from first point.

v3.4 would through same exception too if you call UpdateFromPoints(bool updateGroups, bool updateSegmentCount) overload with true for second arg. We've eliminated the internal segmentCount variable since then, as it was causing bugs when number of control points and number of segments diverge. The SegmentCount property getter now determines value from number of control points, and its setter resets control points to appropriate number.

Anyway, if the exception is not thrown after you directly assign to ControlPoints but due to other operations of the diagram, please give us more details how to reproduce.

Regards,
Slavcho
Mindfusion