[ESS] gutters in the left margin

[Chung-hong Chan]

I actually have the same issue since the last few days.

One thing I found is that the buffer local variable
"left-margin-width" (C-h v left-margin-width) has been automatically
changed to 2 in R buffers, while the global is 0.

I did a search in the ESS source code and I think there hasn't been
any change in that.

So, it remains a mystery to me.