Mouse wheel scrolling inserts characters

Question

I'm using macvim inside tmux inside iTerm2. Basically I just want to be able to scroll the buffer using the mousewheel. I've set

set -g moude-mouse on

in my .tmux.conf, and

set mouse=a
set ttymouse=xterm2

in my .vimrc. Additionally I enabled 'xterm mouse reporting' in iTerm2.

Whenever I use the mouse wheel, vim will switch to insert mode and insert seemingly random characters. I'm guessing vim can't correctly interpret the mouse escape-codes.

The problem also appears outside of tmux and in the default Terminal.app which leads me to believe that it's a vim issue.

I've expiremented with all possible values of ttymouse, none had the desired effect.

Answer 1

Ah, I found the culprit by bisecting my .vimrc file. I had mapped Escape in normal mode to clear search highlighting:

" Clear highlighting on escape in normal mode
nnoremap <esc> :noh<return><esc>

However, that will confuse vim as it tries to parse the mouse's escape codes. So what I ended up doing is taking the solution from this answer, and also mapping:

" needed so that vim still understands escape sequences
nnoremap <esc>^[ <esc>^[

Which will fix that issue.