drawable-terrain testing

["Erik Jessen" <ejessen at adelphia dot net>]

I created two simple test-cases (from simple.g), where I define 3 border
types:

(terrain-type state-border
  (image-name "white")
  (subtype-x river-x)
  (subtype border)
  )

(terrain-type river
  (subtype-x river-x)
  (subtype border)
  )

(terrain-type river-conn
  (subtype-x river-x)
  (subtype border)
  )

In test-case simple02.g, I put:
(table drawable-terrain
  (t* t* true)
  (river          state-border false)
  (river-conn state-border false)
  )

This resulted in state-border always being drawn underneath the two river
types, regardless of which one I drew first in the game designer.  My
reading of the docs led me to believe that in drawable-terrain <t1> <t2>
false meant that
    t1 would not be drawn on top of t2.

In test-case simple03.g, I put:

(table drawable-terrain
  (t* t* true)
  (state-border river          false)
  (state-border river-conn false)
  )

This resulted in exactly the same results as test case 02.

What am I doing wrong, that's not causing state-border to show on top in
case 02?