Diagrams: spurious spacing

[Marcelo Huerta]

Greetings,

I asked previously for some package for creating Nassi-Scheiderman
diagrams. As it was no trace of them in the Lout community :-), I
decided to begin creating my own; not by creating a separate package as
I originally intended, but by using the existing Lout resources, and
using @Filter with a Perl script for easy inclusion in new documents.

As I started I found a disgusting problem. Maybe it's my own
cluelessness, but I have this file (ugliness due to planned scripted
autogeneration):

==================== Cut here ====================
@SysInclude { diag }
@SysInclude { eq   }
@SysInclude { tbl  }
@SysInclude { doc  }

import @Diag
def @NSWhile
    left cond right cuerpo
{
  @Node
  margin { 0c }
  outline {
    AI:: {0 ysize} -- {-2f 1v}
    AD:: {xsize ysize} -- {0 1v}
    BI:: {0 0} ++ {2f 0}
    0 0   0 ysize   xsize ysize   xsize 0   0 0
    BI AI AD
  }
  {
    |2f cond /1.2v | cuerpo
  }
}

@Doc @Text @Begin

@CD
@Diag @Begin
4c @Wide 
-0.5p @Font @HExpand @Tbl
  margin {0c} 
  rule {yes} aformat address@hidden A}
{
@Rowa A {|0.1c @Eq {a sub 1 <-- square } |0.1c}
@Rowa A {|0.1c @Eq {b sub 1 <-- square } |0.1c}
@Rowa A {-1p @Font @I {boolean-expr} @NSWhile -0.1p @Font @HExpand @Tbl 
    margin {0c} rule {yes} aformat address@hidden A}
    { 
      @Rowa A {|0.1c @Eq {a sub 2 <-- square } |0.1c}
      @Rowa A {|0.1c @Eq {b sub 2 <-- square } |0.1c}
    }
}
@Rowa A {|0.1c @Eq {c sub 1 <-- square } |0.1c}
@Rowa A {|0.1c @Eq {d sub 1 <-- square } |0.1c}
}
@End @Diag

@End @Text
==================== Cut here ====================

This intends to be a simple Nassi-Scheiderman diagram. The @NSWhile
should contain the "a sub 2" and "b sub 2" lines. When creating the file
with Lout 3.23, an empty row appears before the "a sub 2" one. I'm at
loss: which function call is creating the gap? Is it solvable?

Thanks in advance.

                       o-=< Marcelo Huerta >=-o