If a download does not open up in its appropriate application, then the problem is probably that the file is
being served with Content-type of 
<code>application/octet-stream</code>

<p>The way to check this is to search the web
for "check html headers"</p>

<p>For example, 
<a href="http://www.icyphy.org/conferences/12/kickoff/iCyPhyKickoffAgenda2012.doc">http://www.icyphy.org/conferences/12/kickoff/iCyPhyKickoffAgenda2012.doc</a>
was being downloaded but the option of  opening with
Word was not offered.</p>

<p><a href="http://web-sniffer.net/">http://web-sniffer.net/</a> showed that the content type was
<code>application/octet-stream</code>.</p>

<p>It turns out that the problem was that icyphy/get.php
was forcing non-text/html files to be octet-stream.</p>

<p>The fix was to create a common function in util.inc.php that handles the passthrough: util_html_passthrough()</p>