Thanks!
Chris
pdftron CosEdit (http://www.pdftron.com/pdfcosedit/index.html). I
remember (it was a long time ago…) the free (trial?) version allowed
viewing the PDF structure, but not changing it.
Enfocus Browser (http://www.enfocus.com/product.php?id=4530). Maybe
not 100% ‘graphical’ (i.e. it does not display the structure as a
tree, although it is a GUI application), but allows to view/ navigate/
modify the internal structure of the PDF.
I’m sure there are others too, you may search sites like planetpdf.com.
Hope this helps,
Dimitri
WindJack Solutions
www.windjack.com
www.pdfscripting.com
HTH, Reinhard