tmux 3.7-rc adds floating panes

Category: Dev tools
Status: developing
Sources: GitHub release, CHANGES
Summary: tmux published a 3.7 release candidate on 2026-06-12. The headline feature is floating panes, which sit above the tiled layout like non-modal popups, are created with a new new-pane command bound to * by default, and behave like ordinary panes. Other changes include a copy-mode-line-numbers option with off, default, absolute, relative, and hybrid modes, run-shell argument expansion as #{1}, #{2}, and a -g flag for kill-session that kills all sessions in a session group.
Why it matters: Floating panes are the first structural layout addition to tmux in several releases and change how popup-style workflows are scripted.
Follow-up: Watch for the tmux 3.7 stable release and any configuration breakage reports from the new pane model.