ESSSpeedbar

To make speedbar show an R buffer’s functions, variables, etc, you need to add R to the set of supported extensions; for instance, add to your .emacs

    (speedbar-add-supported-extension ".R")

By default, speedbar will split the list of functions into groups if there are more than 10. If you do not like this behavior, set the variable

    speedbar-tag-regroup-maximum-length 

to a larger number.

These settings will also work with sr-speedbar, a mode to make speedbar show in the current frame.

Note that you do not need to do anything special for Emacs Code Browser to work with ESS/R.