Proposal: layer-set per page

[David Faure <faure@kde.org>]

For applications like presentation or graphics applications we need to be
able to define layers per page and not only for the whole document as it is in ODF now.

Reasons:
- often you need layers which are special to a one page and are not needed on 
other pages. 
- show only the layers which are needed for the active page and not all layers 
that are there in the document.
- if you delete a layer on a slide only shapes on that slide are deleted in 
case of layers per document you delete shape on this layer in all pages.

All in all it seems quite logical to have layers per page; typically one is
working on one page at a time, and the layout and structure of that page 
can be completely independent from the layout and structure of other pages.

The suggested RelaxNG schema change would be to add

          <optional>
                    <ref name="draw-layer-set"/>
          </optional>

in <element name="draw:page">.

The optional draw:layer-set element from office:master-styles would still have to
be read by applications of course, the per-page layers would simply add to the
document-wide layers.

-- 
David Faure, faure@kde.org, sponsored by Trolltech to work on KDE,
Konqueror (http://www.konqueror.org), and KOffice (http://www.koffice.org).