Tmux pane disappears when opening nvim in its neighboring pane

[agronskiy]

Hello! First, thanks for a wonderful project! So, the issue is as follows:

• the following asciicast Tmux pane disappears when opening nvim in its neighboring pane - asciinema consists in opening tmux with two panes, and firing neovim in one of them. Then repeating in another pane.
• reproducing issue part when replaying the cast in the web player, the idle tmux pane (i.e. not the one where neovim was fired) disappears, also does a part of the pane separator. The pane reappears when switching to it.
• expected flow when replaying in terminal with asciinema play, all works fine -- the panes do not disappear.

Additional info:

• macos 11.5.2 (Big Sur)
• iTerm2 for recording and local replay
• tmux version 3.2a

[ku1ik]

This is interesting. I tested your recording with asciinema play https://asciinema.org/a/V4JMoqkoMNotx983nmt63EzLG on several terminals with following results:

• Alacritty - panes disappear
• Gnome Terminal - panes disappear
• xterm - seems to work fine

Hard to say at a glance what causes this but it's probably due to different handling of some specific, advanced, control sequences tmux uses...

[pocek]

Likely related to DECSLRM which asciinema-player doesn't support. In xterm, vertical split in tmux will use it unless xterm is configured as vt220:

*.vt100.decTerminalID: vt220

Maybe iTerm2 is similar.

[ku1ik]

Aha! That brings us closer to having it fixed. Thanks!

[ku1ik]

Yeah, pretty sure it's DECSLRM missing in avt.

Found related issues for other terminal emulators:

• Alacritty - Implement DECSLRM and DECLRMM alacritty/alacritty#160
• xterm.js - Support DECSLRM (SMGLR, SMGLP, SMGRP) - Set Left and Right Margins for better scrolling performance in multi-pane TUIs xtermjs/xterm.js#4285
• Gnome Terminal / Console - https://gitlab.gnome.org/GNOME/vte/-/issues/2526

It seems currently it's supported in xterm (not xterm.js) and iTerm2.