I missed the support in context, to define exact destination (page 553 
[533],
PDF Reference 1.5 PD) in interactive documents.
The defined types lack the support for destinations, that don't lie on 
the top
of a page.

An example to make it clear...
You have made a PDF document with bookmarks, the focus is set to width
for good readability. Now you press a bookmark for a section and Acroreader
opens the correct page. But hey, where is the section? If it starts at the
lower quarter of the page, it isn't visible at all.

So I tried to change this behaviour, playing around with bookmarks
(as one fuction using destinations). As I'm no TeX wizzard, the result is
very limited. But I hope it's enough to show that there are more or less 
good
reasons for an extension of destinations in context.

Regards,

   Peter