library(zoo)
m <- factor(months(zoo::as.yearmon(time(datasets::sunspots))),
            levels=month.name)
plot(m, datasets::sunspots, axes=FALSE)
axis(2)
axis(1, at=1:12, labels=FALSE)


pdf("Figures/combine-gridedit%1d.pdf", width=4.5, height=4.5, onefile=FALSE)
dev.control("enable")
plot(m, datasets::sunspots)
grid.echo()
grid.edit("graphics-plot-1-bottom-axis-labels-1", 
          y=unit(-1, "lines"), hjust=1, vjust=0.5, rot=60)
dev.off()