[R] split.screen problem and segments in figure margin

["Unternährer Thomas, uth"]

hi,
 
two questions...
 
1. what happens with points()?
    after the split.screen function points() start not at x = 1 (at x = - something)

graphics.off()
x11()
split.screen(c(3, 1))
split.screen(c(2, 1), 1)

screen(3)
plot(dat, type = "n")
screen(4)
plot(dat, type = "n")
screen(2)
plot(dat, type = "n")

dat <- rnorm(1000)

for (i in 1:length(dat)){
  screen(3)
  points(i, dat[i])
  screen(4)
  points(i, dat[i])
  screen(2)
  points(i, dat[i])
}

close.screen(all = TRUE)

I was searching the mail-archives and found the same question but no answers.
Can somebody help me?
 
 
2. Can I draw segments() in the figure margin (not in the plot region).... or can I split my axis(2,...) in 3 with a gap between them? 
 
 
thanks for any help
 
Thomas