The mouse scroll wheel does not work when not in copy mode. I'm not sure whether it is supposed to be working then? When in copy mode, the scroll wheel does work. The problem is that I still need to enter copy mode manually. Is it possible to enter copy mode upon mouse wheel activity? I am using gnome-terminal and the CVS version of tmux. These are my relevant settings:
set -g mouse-select-pane on
setw -g mode-mouse on