Patches to pref->graph

[Willem Ferguson]

Dirk,
I suspect the last of my two patches will not apply. There is a problem 
with character encoding in the raw text of the patch and I have no idea 
how to fix that. The subscript-2 of pO2 consequently appears unreadable.

If the second patch cannot be applied:
If you apply the first of the two patches I will pull the latest version 
of the code from master and rewrite the second patch that removes 
pre-pended space characters.

Kind regards,
willem