no undercurl in tmux #2214

kokostek commented 2025年11月09日 15:17:43 +01:00

Foot Version

foot version: 1.25.0 +pgo +ime +graphemes -assertions

TERM environment variable

'tmux-256color' ('foot' - outside of tmux)

Compositor Name and Version

kwin 6.5.2

Distribution

arch linux

Terminal multiplexer

tmux

Shell, TUI, application

zsh

Server/standalone mode

• Standalone
• Server

Foot config

# -*- conf -*-
font=monospace:size=11
[environment]
[security]
[bell]
[desktop-notifications]
[scrollback]
[url]
[cursor]
[mouse]
[touch]
[colors]
[csd]
[key-bindings]
show-urls-launch=Control+Shift+u
unicode-input=none
[search-bindings]
[url-bindings]
[text-bindings]
[mouse-bindings]

Description of Bug and Steps to Reproduce

When I do printf "\e[4:3mhello world\n" outside of tmux in foot, I see curly underline in the output. When I do the same from tmux session, I see only the straight underline.

In kitty, curly underline appears both inside and outside of tmux.

Some notes:

• I have foot-terminfo package installed.
• I have this line in my .tmux.conf: set -a terminal-features 'foot*:RGB'.

Relevant logs, stacktraces, etc.

No response

### Foot Version foot version: 1.25.0 +pgo +ime +graphemes -assertions ### TERM environment variable 'tmux-256color' ('foot' - outside of tmux) ### Compositor Name and Version kwin 6.5.2 ### Distribution arch linux ### Terminal multiplexer tmux ### Shell, TUI, application zsh ### Server/standalone mode - [x] Standalone - [ ] Server ### Foot config ```ini # -*- conf -*- font=monospace:size=11 [environment] [security] [bell] [desktop-notifications] [scrollback] [url] [cursor] [mouse] [touch] [colors] [csd] [key-bindings] show-urls-launch=Control+Shift+u unicode-input=none [search-bindings] [url-bindings] [text-bindings] [mouse-bindings] ``` ### Description of Bug and Steps to Reproduce When I do `printf "\e[4:3mhello world\n"` outside of tmux in foot, I see curly underline in the output. When I do the same from tmux session, I see only the straight underline. In kitty, curly underline appears both inside and outside of tmux. Some notes: - I have `foot-terminfo` package installed. - I have this line in my `.tmux.conf`: `set -a terminal-features 'foot*:RGB'`. ### Relevant logs, stacktraces, etc. _No response_

krobelus commented 2025年11月09日 18:02:12 +01:00

The unreleased tmux commit 7499d925 (Do not downgrade styled underscores to standard underscore if the terminal does not support them, 2025年05月12日) should fix this specific issue.

I think it's because older versions of tmux check for the Smulx boolean capability in terminfo;
foot's terminfo includes that but the ncurses release is probably a bit behind.

You can probably work around this by adding Smulx to your terminal-features (not sure about the syntax)

$ grep Smulx foot.info
Smulx=\E[4:%p1%dm,

The unreleased tmux commit 7499d925 (Do not downgrade styled underscores to standard underscore if the terminal does not support them, 2025年05月12日) should fix this specific issue. I think it's because older versions of tmux check for the `Smulx` boolean capability in terminfo; foot's terminfo includes that but the ncurses release is probably a bit behind. You can probably work around this by adding Smulx to your `terminal-features` (not sure about the syntax) $ grep Smulx foot.info Smulx=\E[4:%p1%dm,

craigbarnes commented 2025年11月09日 21:13:30 +01:00

You can probably work around this by adding Smulx to your terminal-features (not sure about the syntax).

set -ga terminal-features ',foot:usstyle'

There are several other features you may want to add to this list (all documented in man tmux).

> You can probably work around this by adding `Smulx` to your `terminal-features` (not sure about the syntax). ```sh set -ga terminal-features ',foot:usstyle' ``` There are several other features you may want to add to this list (all documented in `man tmux`).

kokostek commented 2025年11月10日 10:16:58 +01:00

Thanks! foot:usstyle did the trick. I've been scrolling through tmux's man and somehow missed it in the terminal features section.

Thanks! `foot:usstyle` did the trick. I've been scrolling through tmux's man and somehow missed it in the terminal features section.