X positions of boxplot in StatsPlots

This may be a naive way to be constructing them, but I am making boxplots in the following way:

using StatsPlots
x1 = randn(100); # A group
x2 = rand(100); # B group

boxplot(["A"], x1,label="")
boxplot!(["B"], x2,label="")

What I would like to do is to recover (or deliberately set) the x positions of the two boxplot centers so that I could add additional graphical annotations to the figure. It would also be desirable if I could figure out the entire width of the figure (from the left edge of A to the right edge of B).