Size and margin support Landmarks

[noelwelsh]

Can margin and size in Layout support Landmarks in addition to numeric values? I feel this would be make them more useful. E.g. I could set the bounding box to 200% or 50% of the current size.

Tasks

• Investigate the semantics. Does this actually make sense? Would the semantics be the same as using Landmarks for other layout tasks (e.g. on, or above)?
• Implement. Should be fairly straightforward. The same approach as in other layout methods could be taken.
• Document it!