glyph replacement only seems to work for second+ levels if missing glyphs are at
start of run.

e.g see picture and zip of testcases.

Font is "Bitstream Vera Sans" which doesn't contain Chinese of Korean glyphs.
Locale is en_US.UTF-8. (stock SRC680_m155 on normal Fedora Core 4 with
fonts-korean and fonts-chinese installed)

I think that a chinese font is higher in the fallback list than korean. I think
that the first level fallbacks get drawn correctly, but that higher level always
get drawn at position 0, or something similar to this.

Take "ok.odp", the 2nd letter being chinese gets drawn correctly in the right
place, the korean glyph gets drawn at position 0 which is correct. So all looks
well.

In "notok0.odp" all is the same except the order of the characters is reversed,
the chinese glyph gets drawn correctly, but the korean one gets drawn at
position 0 on top of the chinese one.

In "notok1.odp" we have a chinese glyph, a korean one, and the chinese one
again. The chinese ones are placed correctly, while the korean one overlaps the
first glyph again as in notok0.odp

In "notok2.odp" we have a korean glyph, a chinese one, and the korean one again.
The chinese ones are placed correctly, while the first korean one is at position
0, and the second one overlaps the correctly placed chinese glyph


Picture is ok.odp and notok.odp side by side