Window size bug with tmux integration on version >= 3.1.0

• iTerm2 version: >= 3.1.0, the problem first occurred in 3.0.20160815-nightly not present in 3.0.20160814-nightly

• OS version: 10.13.0 (Also occurred on 10.12.x, perhaps others?)

Detailed steps to reproduce the problem:

1. Attach to tmux with integration
2. Create a split tab between two different terminals
3. Maximize one of the sub windows to be full screen in that tab
4. Switch focus to different tab, window, or program, then switch back
5. The "full screen" tab still renders as the whole tab's window, however stty -a shows it's size to be the unmaximized dimensions again, so things like top render the smaller size inside it, and the command line wraps strangely. Re-maximizing the tab will correct the dimensions, and toggling things once more will restore the split view.

What happened: It seems that tmux integration is losing the maximized terminals's dimensions when focus is reacquired. The correct dimensions are present until that point. Perhaps it's just forgetting that the window was maximized to fill the whole tab?

What should have happened: Terminal dimensions should remain the same as the rendering window's dimensions, even when using tmux integration. Things seems to work fine when not using tmux integration mode. This was a regression in the 3.1.x line specifically, as this problem doesn't occur in <= v3.0.15

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mentioned in issue #5063 (closed)

I don't see any changes around 8/14 that could account for this. What version of tmux are you using? Do you have a ~/.tmux.conf file?

Oh, I was looking at august 2017. Yeesh.

So that commit is certainly responsible because it causes us to report the selected pane to tmux. Now I just need to be able to reproduce what you're seeing. So let me know the tmux version and anything about your configuration that might be relevant.

@gnachman Any version after 3.0.20160815-nightly will do it, I spot checked through the posted nightlies until I found the first one that the problem occurred in. It seems to be pretty easy to duplicate, just create split panes in a tab/window, then use View -> Maximize Active Pane, then change focus away and back. When it regains focus, it will reset the terminal size to the unmaximized version, even though the rendering window will continue keeping it's full size. It's also losing more than just the terminal size, as hitting maximize active pane will reset things back to maximized without changing how it draws the window (staying maximized the whole time), and you have to hit it a second time after regaining focus to un-maximize the pane.

tmux version also doesn't seem to matter, occurs with all versions that I've tried (basically 1.8+)

here's my .tmux.conf, though I don't think it actually makes any difference.

# Set the prefix to ^A.
unbind C-b
set -g prefix ^A
bind a send-prefix

# Set keyboard copy to vi mode, and give some vim bindings.
set-window-option -g mode-keys vi
bind-key -t vi-copy 'v' begin-selection
bind-key -t vi-copy 'y' copy-selection
bind P paste-buffer

# Bind appropriate commands similar to screen.
# lockscreen ^X x
unbind ^X
bind ^X lock-server
unbind x
bind x lock-server

# Set ^C as copy to clipboard
unbind ^C
bind ^C run-shell "~/.tmux/clipcopy $(tmux save-buffer -)"

# screen c
unbind c
bind c new-window

# detach ^D d
unbind ^D
bind ^D detach

# displays *
unbind *
bind * list-clients

# next ^@ ^N sp n
unbind ^@
bind ^@ next-window
unbind ^N
bind ^N next-window
unbind " "
bind " " next-window
unbind n
bind n next-window

# title A
unbind A
bind A command-prompt "rename-window %%"

# other ^A
unbind ^A
bind ^A last-window

# prev ^H ^P p ^?
unbind ^H
bind ^H previous-window
unbind ^P
bind ^P previous-window
unbind p
bind p previous-window
unbind BSpace
bind BSpace previous-window

# windows ^W w
unbind ^W
bind ^W list-windows
unbind w
bind w list-windows

# quit \
unbind \
bind \ confirm-before "kill-server"

# kill K k
unbind K
bind K confirm-before "kill-window"
unbind k
bind k confirm-before "kill-window"

# redisplay ^L l
unbind ^L
bind ^L refresh-client
unbind l
bind l refresh-client

# More straight forward key bindings for splitting
unbind %
bind | split-window -h
bind v split-window -h
unbind '"'
bind - split-window -v
bind h split-window -v

# History
#set -g history-limit 65536
set -g history-limit 4096

# Pane
unbind o
unbind ^o
bind C-s select-pane -t :.+

# Terminal emulator window title
set -g set-titles on
set -g set-titles-string '#S:#I.#P #W'

# Status Bar
set -g status-bg black
set -g status-fg white
set -g status-interval 1
set -g status-left '#[fg=green]#H#[default]'
set -g status-right '#[fg=yellow]#(cut -d " " -f 1-4 /proc/loadavg)#[default] #[fg=cyan,bold]%Y-%m-%d %H:%M:%S#[default]'

# Notifying if other windows has activities
setw -g monitor-activity on
set -g visual-activity on

# Highlighting the active window in status bar
setw -g window-status-current-bg red

# Clock
setw -g clock-mode-colour green
setw -g clock-mode-style 24

# :kB: focus up
unbind Tab
bind Tab select-pane -t :.+
unbind BTab
bind BTab select-pane -t :.-

# " windowlist -b
unbind '"'
bind '"' choose-window


# Order windows similar to Linux's TTY keybindings
#set-option -g base-index 1

set-option -g pane-active-border-fg red
set-option -g pane-active-border-bg default
set-option -g pane-border-fg white
set-option -g pane-border-bg default

set-option -g status-left-length 12

bind R source-file ~/.tmux.conf \; display-message "Config reloaded..."

setw -g mode-mouse on
set-option -g mouse-select-pane on

# SSH Agent fixup
set -g update-environment "DISPLAY SSH_ASKPASS SSH_AGENT_PID SSH_CONNECTION WINDOWID XAUTHORITY"
set-environment -g 'SSH_AUTH_SOCK' ~/.ssh/ssh_auth_sock


# Shift+PgUp/PgDn for scrolling
set -g terminal-overrides 'xterm*:smcup@:rmcup@'

Even with your .tmux.conf, I still can't reproduce it. Could you make a debug log that reproduces the issue? Instructions are at https://iterm2.com/debuglog. Thanks!

Here's a debuglog.txt

I've tried to keep it as short as possible, let me know if you need anything more.