SOLVED:
WindowScale = comp(“MainComp”).layer(“BasicWindow”).transform.scale;
result = transform.scale[1] / (WindowScale[1] * 0.01);
[result,result]
I have a little vibrance of the layer when i animate the scale but it can be acceptable, at less for now…
Sorry for the thread, its was very easy one but my head is out of his limits today.
Thanks if anyone was thinking of helping me, I leave the question open about the vibration in case you encourage to answer..