[R] multiple plots in png output

[Karen L. Updegraff]

I am using R version 1.9.1 under Linux.

In the past I have had no problem saving a multi-plot page to a postscript
or png device. However, the last time I did this may have been under a
previous version of R. Presently nothing I do seems to succeed in saving
multi-plots, defined (for example) with 
mfrow=c(2,2) ... plot(..) .. plot(..)

The same problem has occurred using hist() and plot().
These are not plots that lend themselves to a lattice format, so that
is not really an option.  The multi-plot page displays fine with
the default (x11) graphics device but in the saved file only the last
plot shows up.

The only suggestion of a problem that I found in the R documentation was
a warning that png and "similar devices" would tend to save only the
last page of a multi-page plot, unles you used something like "%d" to
indicate the file sequence. There are no details on how or where that
option might be used. R documentation frequently seems to go out of its way
to be opaque.

Is this a bug that was introduced with v 1.9.1, and if so has it
been fixed in more recent releases? Alternatively, is there a
workaround which is not documented?

Suggestions appreciated.
Karen