impoint issue: setPosition in a addNewPositionCallback function

Hi

Is there a way to use setPoint in a addNewPositionCallback function. I want to reallocate a draggable point (setting dynamic restrictions) so that the impoint is restricted for example to a certain slope movement, or attached to a certain curve.

This is the general idea, where BaP is a global array of imPoints and B2Ba is an angle:

addNewPositionCallback(BaP(2),@Interact);

function Interact(Pos)

global BaP B2Ba

P=getPosition(BaP(1));

setPosition(BaP(2),[Pos(1,1) P(1,2)-Pos(1,1)*tan(B2Ba)]);

But it doesn't get repositioned as i wanted. Checking the impoint object, the property insideSetPoint is not letting me change the current position further using setPosition. Is there a workaround for this? Or any way of getting the desired behaviour?