For a lineup box, is it possible to add an entry which spans across multiple "cells"?
to get this design:

instead of this one:

pb = Expr(
Panel Box( "", Spacer Box( Size( 20, 20 ) ), <<background color( "dark blue" ) )
);
sb = Expr(
Spacer Box( Size( 20, 20 ) )
);
New Window( "test design",
Lineup Box( N Col( 4 ),
pb, pb, pb, pb,
pb, pb, pb, pb,
pb, sb, sb, pb,
pb, pb, pb, pb, )
);