### Name: journalpng
### Title: Produce a device for producing artwork for presentations and
###   journals
### Aliases: journalpng screenpng
### Keywords: misc

### ** Examples

   ## Not run: 
##D      journalpng(file="results/figure1.png"); # starts a new device
##D      trad.scatter.plot(exprs(eset)[,1],exprs(eset)[,2])
##D      dev.off();    # writes the file at this point.
##D   
## End(Not run)