As you can see in the results of processing the ConTeXt code below, the
footnote gives an "Overfull \hbox" warning. And the overflow is always
exactly 426.78743pt too wide (at least in my documents).
-----------------------------------------------
\starttext
A test\footnote{Just testing.} of footnotes.
\stoptext
-----------------------------------------------
Running `ConTeXt Full' on `test' with ``context --autopdf "test"''
This is LuaTeX, Version beta-0.46.0-2009112722
\write18 enabled.
(test.tex
ConTeXt ver: 2009.12.03 00:41 MKIV fmt: 2009.12.12 int: english/english
system : cont-new loaded
(C:/context/tex/texmf-context/tex/context/base/cont-new.tex
systems : beware: some patches loaded from cont-new.tex
(C:/context/tex/texmf-context/tex/context/base/cont-new.mkiv))
system : cont-fil loaded
(C:/context/tex/texmf-context/tex/context/base/cont-fil.tex
loading : ConTeXt File Synonyms
)
system : cont-sys.rme loaded
(C:/context/tex/texmf-context/tex/context/user/cont-sys.rme
(C:/context/tex/texmf-context/tex/context/base/type-lua.tex)
(C:/context/tex/texmf-context/tex/context/base/type-tmf.tex
(C:/context/tex/texmf-context/tex/context/base/type-tmf.mkiv))
(C:/context/tex/texmf-context/tex/context/base/type-siz.tex
(C:/context/tex/texmf-context/tex/context/base/type-siz.mkiv))
(C:/context/tex/texmf-context/tex/context/base/type-otf.tex
(C:/context/tex/texmf-context/tex/context/base/type-otf.mkiv)))
system : test.top loaded
(test.top)
fonts : preloading latin modern fonts
bodyfont : 12pt rm is loaded
language : language en is active
systems : begin file test at line 1
Overfull \hbox (426.78743pt too wide) in paragraph at lines 2--2
[]
fonts : resetting map file list
{C:/context/tex/texmf-context/fonts/map/pdftex/context/original-empty.map}
fonts : using map file: original-base
{C:/context/tex/texmf-context/fonts/map/pdftex/context/original-base.map}
fonts : using map file: original-ams-base
{C:/context/tex/texmf-context/fonts/map/pdftex/context/original-ams-base.map}
fonts : using map file: original-ams-euler
{C:/context/tex/texmf-context/fonts/map/pdftex/context/original-ams-euler.map}
fonts : using map file: original-public-lm
{C:/context/tex/texmf-context/fonts/map/pdftex/context/original-public-lm.map}
fonts : using map file: lm-math
{C:/context/tex/texmf/fonts/map/dvips/lm/lm-math.map}
fonts : using map file: lm-rm
{C:/context/tex/texmf/fonts/map/dvips/lm/lm-rm.map}
system : xmp data not flushed (needs luatex upgrade)
!pages : flushing page, realpage 1, userpage 1
systems : end file test at line 3
system : cont-err loaded
(C:/context/tex/texmf-context/tex/context/base/cont-err.tex
systems : no file 'cont-sys.tex', using 'cont-sys.rme' instead
)
)