From the QuickCircle script, what does this line do?
pointpicker.stickToSurfacesMode = 'max';

Is there some way to lock the "on surface" snap, when placing say a point, to keep it on the surface of a surface, and still
snap in the x and y directions to other objects? I guess the 3D window would have to be looking straight down.

(I rediscovered that the object snap button has an arrow on top, for selecting the 14 snaps, which is in the documentation.)