Point at absolute screen position
At present a locus of point A can only be drawn, if A is depending on another point B. If it is depending on a slider value a locus is not possible.
As a substitute we can use the affine ratio of a point on a segment. The only thing that's missing now is: We cannot fix points at a certain absolute screen position as we can do with sliders.
Is it possible to add this feature?
P.S. If there were functions to get the actual coordinates of the upper left and lower right corner of the drawing pad, this would do as well.