I would Align using the option to "Align and distribute from the object outline."
That might not be as convenient as what you have in mind - but it exists right now.
Eskimo, I didn't take it to mean the same as you're thinking. I see the problem like this. You have 2 shapes, Shape A is a closed shape and the outline "Position" is set to "Inside". Shape B is an open line segment and since you cannot assign it to be an "Inside" outline you therefore cannot align it to the top of shape A and have the outline printable area on the same plane. You'd have to move the line segment half the distance of the outline thickness.