How to avoid long margin notes running into the footer in ConTeXt?

Question

it's me again. :) Still trying to set up a ConTeXt environment file for a book layout.

I have now run into a problem that I wouldn't have thought would appear. Here's a MWE:

\usemodule[visual]

\mainlanguage[de]
\language[de]
\definecolor[lightbrown] [r=0.83, g=0.76, b=0.71]

\setuppapersize[A4][A4]
\setuplayout
[
  backspace=11.67mm,        width=131.25mm,
  topspace=21.21mm,         height=254.57mm,
  headerdistance=13pt,      header=13pt,
  footerdistance=13pt,      footer=13pt,
  rightmargindistance=13pt, rightmargin=39.5mm,
]

\setuppagenumbering[alternative=doublesided, location=]

\setupmargindata[
  style=\ss\tf,
  color=lightbrown,
  stack=continue,
]

\starttext

\chapter{Testing Margin Notes}

\input{knuth}

\input{knuth}

\input{knuth}

\inouter{\input{knuth}}

\input{knuth}

\input{knuth}

\input{knuth}

\stoptext

And here's how this looks like:

I'm sure, you can see the problem: The margin note that I placed in the outer margin on the first page is too long for the margin area and reaches into the footer, down to the end of the page.

Now, I do realize that this is one long margin note, and margin notes won't usually be that long. However, if I understand it correctly, this problem can occur, even if the margin notes are as short as, say, two or three lines: As soon as they are placed close enough to the end of the text area, they will run into the footer.

Frankly, I wouldn't have thought that I would have to deal with a low-level typesetting problem such as this. In my opinion, unless the system can solve situations like this (maybe by shifting the margin notes upwards a bit or by breaking them across pages), margin notes are pretty unusable. So, I'm thinking I must be missing something. Is there a good solution for this?

Thanks in advance.

UPDATE: As I mentioned in a comment below, I do realize that margin notes crossing pages is difficult to achieve for various reasons. But that's not what I need, anyway. All I need is a somewhat automatic way for preventing really short margin notes (say, three or four lines) to extend below the end of the text area. The way margin notes currently work (please correct me, if I'm wrong) means, I will always have to manually tweak their position, if, by chance, they end up too far down on the page. It's this manual intervention that I would like to avoid.

Answer 1

AFAIK, it is not possible to split margin notes across pages. So, if you have a big margin note (or if margin note occurs near a page boundary), there are two possibilities:

1. Shift the margin note up using voffset key or using line key. For example:

   \inouter[voffset=-25\lineheight]{\input{knuth}}
   

   or

   \inouter[line=-25]{...}
   

   It may be possible to automate this (typeset the margin note, measure its height and if the height is greater than the number of lines left on the page, shift the note up), but such a method will not work if there are multiple long margin notes.

2. Place the margin notes to the top of where they are anchored (rather than to the bottom). For example, use

   \inouter[method=top]{....}
   

   or set it globally using \setupmargindata[inouter][method=top]. Variants such as method=depth or method=height also work. But this just moves the problem to a different area. Now margin notes that appear too close to the top may overflow.

In short, you need manual intervention. If you can come up with a robust algorithm on how to place margin notes, then it should be relatively simple to implement it (see typo-mar.lua for current implementation).

Note: In general, you may want to add dy=\lineheight or something similar so that there is some space between the stacked notes.