[protext] Update pdf output file

[Karl Berry]

In addition to Thomas's reply ...

    the pdf output file cannot be updated while the last pdf output is
    still opened (by pdf reader or adobe acrobat).

I'm not sure if this will appeal, but I can think of two other options:

1) use the SumatraPDF reader for Windows, which has a reload feature.
   http://blog.kowalczyk.info/software/sumatrapdf/

2) use TeXworks (http://tug.org/texworks), which has a builtin PDF
   reader and lots of other nifty features.

Hope this helps,
Karl