What's New in tmux 3.6

Fresh

Field	Value
Current Release	tmux 3.6b
Released	2026-05-20
Previous Stable	tmux 3.5a
Last Updated	2026-05-26

This page summarizes the user-facing changes across the 3.6 release line (3.5a to 3.6, then the 3.6a and 3.6b maintenance releases). It is a curated highlight reel, not the full changelog. For the complete list, read the CHANGES file in the tmux source tree.

Upgrade first

Check your version with tmux -V. If it reads tmux 3.5 or older, see SOP-001: Installation to upgrade to 3.6b.

Headline Features

Pane Scrollbars

Panes can now show a character based scrollbar with a draggable slider that reflects scroll position and content size.

# Always show scrollbars
set -g pane-scrollbars on

# Show only in copy mode or view mode
set -g pane-scrollbars modal

# Side to display on (left or right)
set -g pane-scrollbars-position right

# Style: foreground = slider, background = track; width and pad attributes supported
set -g pane-scrollbars-style 'fg=#89b4fa,bg=#313244,width=1,pad=0'

Value	Behavior
off	No scrollbar (default)
on	Visible all the time; pane is narrowed and text reflowed
modal	Appears only in copy or view mode

See SOP-004: Pane Management for the full walkthrough.

Tiled Layout Column Limit

The new tiled-layout-max-columns window option caps how wide the tiled layout grows before stacking panes into extra rows.

# Never use more than 3 columns in the tiled layout
setw -g tiled-layout-max-columns 3

# 0 (default) means no limit
setw -g tiled-layout-max-columns 0

Automatic Dark / Light Theme Detection

tmux now supports terminal mode 2031 to report whether the terminal is in dark or light mode, and guesses from the background colour on terminals that do not support the escape sequence. This lets a configuration adapt its colours to the host terminal theme.

Clock With Seconds

The clock (Ctrl+b t) can now display seconds.

set -g clock-mode-style 24-with-seconds
# Also: 12, 24, 12-with-seconds

Nicer Default Status Lines

The default second and third status lines have been improved, so a stock tmux looks better before any customization.

Copy Mode Improvements

• selection-mode command sets the selection mode (character, line, block) explicitly while in copy mode.
• Centre the cursor commands recenter the viewport on the cursor in copy mode.
• Case insensitive search now works in modes the same way as copy mode: an all lowercase search term matches case insensitively (emacs style).
• -C and -P flags on copy commands: -C stops the command from sending text to the clipboard and -P stops it from adding a paste buffer.
• -y flag disables confirmation prompts in modes.
• New styling options: copy-mode-position-style, copy-mode-selection-style, and copy-mode-position-format to control the look of the position indicator and selection.
• The mouse wheel no longer enters copy mode while in the alternate screen.

See SOP-005: Copy Mode for usage.

New and Changed Options

Option	What it does
pane-scrollbars	Per pane scrollbar: off, on, or modal
pane-scrollbars-position	left or right
pane-scrollbars-style	Scrollbar colours, width, and pad
tiled-layout-max-columns	Max columns in the tiled layout (0 = unlimited)
clock-mode-style	Adds 12-with-seconds and 24-with-seconds
codepoint-widths	Override the display width of individual Unicode codepoints
input-buffer-size	Size of the input buffer
initial-repeat-time	Longer first repeat for repeatable keys, then reduced
no-detach-on-destroy	Client option for detach-on-destroy behavior
default-client-command	Command used when tmux runs without a command
prompt-cursor-style / prompt-cursor-colour	Style the command prompt cursor
variation-selector-always-wide	Control VS16 wide character handling
pane-border-lines spaces	New value that draws pane borders with spaces

Style System

• set-default style attribute replaces the current default colours and attributes completely.
• noattr attribute controls whether style attributes are ignored or applied (used in mode-style).
• Uppercase letters are now allowed in gray/grey colour names.

New Command Flags

Command	Flag	Effect
command-prompt	-l	Disable splitting input into multiple prompts
display-popup	-k	Any key dismisses the popup once the command exits
run-shell	-E	Forward stderr as well as stdout
capture-pane	-M	Capture from the copy mode screen
display-message	-C	Update the pane while the message is displayed

Format Improvements

• New buffer_full and sixel_support format variables.
• Boolean expressions support arbitrarily many && and || arguments, plus ! (not) and !! (not-not).
• #? conditionals gain else if support and a default empty string when no else value is given.
• W, P, and L loop operators can now sort.

Tree Mode

• S-Up and S-Down move windows in tree mode.
• Index numbers are aligned in trees for readability.
• New tree-mode-preview-format option configures the preview indicator.

Maintenance Releases

3.6a (bug fixes)

• Fixed a buffer overread and an infinite loop in format processing.
• Restored drag in the alternate screen.
• Corrected mouse y offset when the status line is at the top.
• Fixed horizontal mouse resizing with pane status lines on.
• FreeBSD compile fix.

3.6b (bug fix)

• Removes images from the correct list when they are removed while in the alternate screen.

See Also

• SOP-001: Installation
• SOP-004: Pane Management
• SOP-005: Copy Mode
• SOP-006: Configuration