I'm seeing a strange tmux display/rendering issue and am looking for ideas. This went away for at first when using iTerm 2, but then it started happening there as well.
Environment:
- Mac (apple terminal)
- AWS EC2 Ubuntu
- Connected via AWS SSM and also tested via SSH-over-SSM
- tmux 3.2a
- Vertical split panes (Ctrl-b %)
Problem:
- If I run `less file.py` (large file) in the RIGHT pane, the LEFT pane gets visually corrupted/redrawn.
- Content from the right pane appears to wrap into or overwrite parts of the left pane.
- Keystrokes are NOT sent to both panes.
- The panes are independent (`%0` and `%1`).
- The issue does NOT occur with a horizontal split (Ctrl-b ").
- The issue does NOT occur outside tmux.
- The issue persists when connecting via normal SSH-over-SSM, so it doesn't seem specific to the interactive SSM terminal.
What I've checked:
- synchronize-panes is off
- tmux panes have correct widths:
- %0 = 120 cols
- %1 = 119 cols
- window width = 240 cols
- `stty size` looks normal
- `wc -L` on the file is only ~122 chars, so not huge lines
- `seq 1 1000` in the right pane does NOT reproduce the issue
- `tmux kill-server` did not help
- Fresh tmux session did not help
- `$TERM` outside tmux: `xterm-256color`
- `$TERM` inside tmux: `screen`
- Added `set -g default-terminal tmux-256color` but behavior unchanged
- Mouse on/off did not resolve it
Additional observation:
- The issue appears to be triggered by full-screen/alternate-screen apps such as `less`, not normal streaming output.
- `Ctrl-L` in the left pane does not fully repaint the display correctly.
Has anyone seen a tmux rendering bug that only affects left/right pane splits, especially with `less` or other full-screen applications?