Here at my Institute, we usually have several versions of genuine Firefox
installed on an NFS server so that users can choose more recent versions
than that provided within Debian, if they wish.

They also run several applications which wish to load URLs into the user's
web browser.  The problem is that these applications become very unreliable
because iceweasel and genuine firefox use different application id's, so
applications which try 'firefox http://some.url.example.com' only work if
the version of firefox being invoked happens to be of the same sort as
whichever browser they're already running.  So, if they run iceweasel first,
say through the desktop menu, then they can only open additional URLs by
invoking another copy of iceweasel.  Invoking genuine firefox results in
'Firefox is running but not responding' errors.

The converse is also the case; if the user runs genuine firefox first,
iceweasel fails to open further URLs (the precise error is slightly
different).

Presumably this is further fall-out from the 'fix' to #408883 way back.

Short of writing some ugly hack wrapper script which parses the output of
xwininfo and then starts whichever copy of firefox/iceweasel with the
correct -a parameter to match the application id, is there anything that
can be done to at least make iceweasel still use the same application ID
as genuine firefox?

This issue also causes a significant interoperation problem between Debian and
other operating systems; the same thing happens if I start iceweasel on my
Debian workstation, ssh to an Ubuntu server and use the Ubuntu firefox to try
to open a new URL.

Regards,

Tim