Bg.Rd
Paints the background of the plot, using either the figure region, the plot region or both. It can sometimes be cumbersome to elaborate the coordinates and base R does not provide a simple function for that.
Bg(col = "grey", region = c("plot", "figure"), border = NA)
the color of the background, if two colors are provided, the first is used for the plot region and the second for the figure region.
either "plot"
or "figure"
color for rectangle border(s). Default is NA
for no borders.