leaders with leader-pattern="use-content"

[Manuel Mall <mm...@arcus.com.au>]

While simple cases for leaders with leader-pattern="use-content" work 
there are a few more difficult to attack gremlins left.

When it comes to Knuth line breaking leaders are modelled as non 
breaking elastic glue. This allows for leaders under justification to 
fill the remaining space and works fine.

However lets take this example:
<fo:block>
  <fo:leader font-size="24pt" leader-pattern="use-content">x</fo:leader>
  The rest of the line
</fo:block>

Because the leader just becomes a piece of Knuth glue the Line LM 
doesn't know that it is actually a "24pt" font and doesn't calculate 
the line height correctly. Of course this is 'getting worse' when one 
thinks that the leader could contain nested inlines of different 
sizes/alignment/baselines/... All this information which is in some 
form or another normally used by the Line LM to calculate the line 
height and by the inline LMs to perform vertical alignments is not 
used.

Don't think this is urgent and there is a disabled test case now for it.

Are there other cases where we could have similar problems, i.e. the 
Knuth sequences not carrying all the information expected because some 
substitution is done - page number citations, markers, ....?

Manuel