The libpng12.0.dylib hoo-hah.

Rolf,

I have no expertise in X11, and can use it (I don't normally, it seems much slower than quartz) the most technical thing I have done is install R installation using the installer from r.research.att.com but if it helps you in a moment of desparation!

My reading of the discourse appears to me to indicate that I should
be able to remedy the problem by running System Update.  I found the
menu item for that and clicked on it.  I got a pop-up window listing
the software for which updates are available.  None seems to have
anything to do with X11 or with libpng12.0.dylib.  I have attached
a screen shot of this pop-up window in pdf format.

I am running 10.6.3 - Apple updates routinely seem to include all sorts of very small tweaks and updates here and there. I don't really understand why my sessionInfo() output is the same as yours - x86_64-apple-darwin9.8.0.

sessionInfo()

R version 2.10.1 Patched (2010-02-01 r51089) 
x86_64-apple-darwin9.8.0 

locale:
[1] en_AU.UTF-8/en_AU.UTF-8/C/C/en_AU.UTF-8/en_AU.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] maptools_0.7-34   lattice_0.18-3    foreign_0.8-40    rgdal_0.6-26      sp_0.9-62         sna_2.1-0        
[7] network_1.4-1     RPostgreSQL_0.1-6 DBI_0.2-5

One item that I guess might have some impact is for the whole operating
system!  The item says that Mac OS X 10.6.3 is available.  (I'm currently
running 10.6.2.)  I hesitate to try this, since I'm not sure what other
difficulties would result from so doing.  And I'm not sure how long it
would take.  Hours?  And doesn't one have to ***pay*** for OS updates?

at 438 MB I guess you could argue that you have to pay, especially if you are not on broadband. But you don't have to pay anything to Apple for the minor digit upgrades ( ie 10.6.2 -> 10.6.3)

So can anyone suggest how I might get the appropriate up-to-date version
of libpng12.0.dylib in place on my system?

I have it - no idea where it came from , but I'd try the upgrade as you have identified. In fact I seem to have all the following:

libpng.3.35.0.dylib
libpng.3.41.0.dylib
libpng.3.dylib
libpng.dylib
libpng12.0.35.0.dylib
libpng12.0.41.0.dylib
libpng12.0.dylib
libpng12.dylib


I hope this is some help.

cheers

Ben