4) Managing the association out-of-line areas (footnotes and floats) with the FONode/Area in which it was defined and the higher-level areas (e.g. before-float-reference-area, footnote-reference-area, main-reference-area) which are juggled as a result of the lower-level contents.
Footnotes are basically float-after areas. Both float before and footnotes are not much of a problem except for multi column layout (and, well, in tables). In multi-column layouts, the equal width of the column should allow reassigning content after decreasing column height without doing a complete re-layout. Side floats, of course, are a real pain, especially if you want to do conflict resolution properly.
J.Pietschmann
