windows.options(record=TRUE)

tmp <- data.frame(x=1:5, y=rnorm(5))
plot(y ~ x, data=tmp, pch=16, cex=3,
     col=c('blue','red','green','salmon','hotpink'))
plot(  ~ x, data=tmp, pch=16, cex=3,
     col=c('blue','red','green','salmon','hotpink'))

methods(plot)
plot.data.frame <- function(x, ...) boxplot(x)
plot(  ~ x, data=tmp, pch=16, cex=3,
     col=c('blue','red','green','salmon','hotpink'))
## no difference
ls()
rm(plot.data.frame)

## turn on ess-tracebug and ess-developer
## add graphics with C-c d-a gr
## C-c d s the fake.plot.data.frame.r file into graphics

ls()
plot(  ~ x, data=tmp, pch=16, cex=3,
     col=c('blue','red','green','salmon','hotpink'))

## the plot.formula method without a y variable calls the
## plot.data.frame method inside the namespace.  It doesn't see the
## version in the global environment.  C-c d s places the functions
## inside the namespace.