[pstricks] drawing ncbox* in background

[Christian Stork]

Hi,

I'm new to pstricks, so please forgive me if I overlooked something.

I'd like to highlight a path within a pstree.  Ideally I would like to
use something like

...
%draw tree with nodes named n1, n2, n3,..
...
\ncbox*[linecolor=red]{n1}{n2}
\ncbox*[linecolor=red]{n2}{n3}
...

Problem is that ncbox* fills the area on top the tree.

Is there a way to change the backgroundcolor with ncbox?  

(More generally, is there a way to draw in layers with pstricks?)

Thanks for you time and expertise,
Chris

-- 
Chris Stork <><><><><><><><><><><><><>  http://www.ics.uci.edu/~cstork/
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