The Snap Attach Distance defines within what distance
your cursor will snap to a point when the Snap to Intersection or Object
modifiers are active. Note that the distance defined is a screen distance,
in other words if you have this snap attach distance set to 40 it means
that the attach distance is approximately 40 pixels on your screen, regardless
of the zoom on your document. Snap attach distances between 20 and 50
are recommended.