[Rd] trace trap (PR#3324)

[p.e.brown at lancaster.ac.uk]

Hi.  I wanted to add two new columns to a data frame, and ended up 
crashing R

 > temp <- data.frame(a=1:3, b=4:6)
 > temp[[c("d","e")]] <- NA

Process R trace trap at Mon Jun 23 16:32:36 2003

I know the above code isn't very elegent, but it shouldn't crash R.

I managed to add the new columns doing

 > temp[,c("d","e")] <- NA

'day

patrick