[trunk] Header / footer need margins

The current trunk implementation of header / footer styles / text styles makes very difficult to place page numbers (and other header/footer text) at the desired spot in the page.

Header, for instance, is always placed at the 0,0 page point.

Vertically, it can be moved with "Styles | Edit text styles... | Header | Offset Y".
Horizontally, there seems to be no way: if the corresponding Offset X value is other than 0 and headers are different for odd and even pages, either the odd or the even page number ends outside the page edge.

The current work-around is to add blank spaces after/before the page number in odd/even headers, but this is largely sub-optimal.

A) One solution could to have proper margin settings (left and right) for the four combinations of odd/even header/footer.

B) Another solution -- perhaps less intuitive but possibly quicker to implement -- could be to internally use the odd/even page margins for the odd/even header/footers, from which each could be moved by the Offset X and Y values quoted above.

On the fly, I would say both solutions would achieve the same flexibility.

Thanks,

M.