Select text in Tmux doesn't copy content to clipboard

[kevinkirkup]

Describe the bug
In version 0.39, selecting text with a mouse would automatically copy the text to the clipboard.
This is now broken in 0.40.x

To Reproduce

1. Open tmux within Kitty terminal.
2. Select some text.
3. Text can now be pasted from the clipboard

Screenshots
If applicable, add screenshots to help explain your problem.

Environment details

kitty 0.40.1 (2bab0b7b18) created by Kovid Goyal
Darwin xxx 24.3.0 Darwin Kernel Version 24.3.0: Thu Jan  2 20:24:23 PST 2025; root:xnu-11215.81.4~3/RELEASE_ARM64_T6020 arm64
ProductName:            macOS ProductVersion:           15.3.2 BuildVersion:            24D81
OpenGL: '4.1 Metal - 89.3' Detected version: 4.1
Frozen: True
Fonts:
  medium: PragmataProMonoLiga-Regular: /Users/kevinkirkup/Library/Fonts/PragmataPro_Mono_R_liga.otf
          Features: ()
    bold: PragmataProMonoLiga-Bold: /Users/kevinkirkup/Library/Fonts/PragmataPro_Mono_B_liga.otf
          Features: ()
  italic: PragmataProMonoLiga-Italic: /Users/kevinkirkup/Library/Fonts/PragmataPro_Mono_I_liga.otf
          Features: ()
      bi: PragmataProMonoLiga-BoldItalic: /Users/kevinkirkup/Library/Fonts/PragmataPro_Mono_Z_liga.otf
          Features: ()
Paths:
  kitty: /Applications/kitty.app/Contents/MacOS/kitty
  base dir: /Applications/kitty.app/Contents/Resources/kitty
  extensions dir: /Applications/kitty.app/Contents/Resources/Python/lib/kitty-extensions
  system shell: /bin/zsh
System color scheme: light. Applied color theme type: none
Loaded config files:
  /Users/kevinkirkup/.config/kitty/kitty.conf

Config options different from defaults:
allow_remote_control socket
copy_on_select       clipboard
font_family          family='PragmataPro Mono Liga' postscript_name=PragmataProMonoLiga-Regular
font_size            12.0
listen_on            unix:/tmp/kitty
Changed shortcuts:
        cmd+k →  clear_terminal_and_scrollback
        ctrl+cmd+, →  reload_config
        ctrl+cmd+l →  clear_screen
        opt+cmd+k →  clear_scrollback
        opt+cmd+r →  reset_terminal
        shift+cmd+/ →  open_kitty_website
Colors:
        color0               #6a6a6a   
        color1               #e64217   
        color10              #b2e267   
        color11              #fce95b   
        color12              #99caff   
        color13              #cd31cc   
        color14              #94edfe   
        color15              #e2e2e2   
        color2               #b2e267   
        color3               #d9c84e   
        color4               #5a7799   
        color5               #ff7df3   
        color6               #78becc   
        color7               #d5d5d4   
        color8               #323131   
        color9               #ff491a   
        cursor               #c7c7c7   
        cursor_text_color    #fffefe   
        foreground           #e1e2e1   
        selection_background #c1ddff   
        url_color            #005bbb   

Important environment variables seen by the kitty process:
        PATH                                /Applications/kitty.app/Contents/MacOS:/usr/bin:/bin:/usr/sbin:/sbin
        LANG                                en_US.UTF-8
        SHELL                               /bin/zsh
        DISPLAY                             /private/tmp/com.apple.launchd.RdWqNfJr0Y/org.xquartz:0
        USER                                kevinkirkup

This debug output has been copied to the clipboard

Additional context
Seeing the same behavior with --config NONE

[kovidgoyal]

First of all with --config=NONE you cant select and copy to clipboard
since that functionality requires copy_on_select yes in kitty.conf

Secondly, copy_on_select only works for kitty selections. If the
program you are running in kitty manages the selections itself, then it
doesn't apply. I dont use tmux but, as far as I know, it doesnt manage
mouse selections, at least with default config.

On my macOS amchine, running

kitty --config=NONE -o copy_on_select=y tmux

and selecting text copies it to clipboard as expected.
If you have some config in tmux to manage the mouse, then I will need a
minimal tmux config to reproduce with.

As it stands, I cannot reproduce.

[kevinkirkup]

This isn't related other than copy_on_select.

It works on 0.39.0 and now fails on 0.40.x.
So something obviously changed.

[kovidgoyal]

No doubt, but in order to help you, I need a way to reproduce your
issue.

[adigie]

Hi @kovidgoyal, I see the same issue since 0.40.1. Here is a minimal repro:

tmux.conf

set -g mouse on

Command

kitty --config=NONE tmux -f ./tmux.conf

tmux server must not be running, as the provided config won't be used.

Result

On 0.40.0 if I select some text, it's copied to the clipboard.
On 0.40.1 it does not work. Adding -o copy_on_select=y does not change anything.

[adigie]

Thanks @kovidgoyal!