Getting xpdf point-and-click to go back to existing emacs window

[Nick Payne]

I've been setting up emacs and xpdf for use with lilypond 17.25 on 
Ubuntu 13.04, using emacs 24.3, and the Debian install files for xpdf 
3.03 and libpoppler19. Most things seem to be working - I have syntax 
highlighting, I can run Lilypond with C-c C-l, and C-c C-s opens the PDF 
output in xpdf. But when I click on a hyperlink in the PDF output, what 
happens is that a new  emacs window opens with another copy of the ly 
source file and the cursor is positioned there. If I click on another 
hyperlink, yet another emacs window with yet another copy of the source 
opens...and so on.

What do I need to configure to get the hyperlink to go to the ly source 
file that I already have open in emacs? I followed the instructions at 
http://www.lilypond.org/doc/v2.17/Documentation/usage/configuring-the-system-for-point-and-click 
to do the configuration for emacs and xpdf.

Nick