I’m a vim+tmux user/believer! I recently installed OS X el capitan and updated/upgraded most of my homebrew Cellar to put it like that. Now, by doing that I got tmux 2.1 where apparently mouse-mode/mode-mouse is completely rewritten. I don’t use the mouse for much, but still nice to have when resizing panes.

So, what you need is to change your .tmux.conf

set -g mode-mouse on
set -g mouse-resize-pane on
set -g mouse-select-pane on
set -g mouse-select-window on


set -g mouse on

Short and sweet! :) My dotfiles github repo is already updated!