Set OPTION for all sessions
misc
// what it does
`set -g OPTION` (short for `set-option -g`) sets a session option in the global session table, so it applies to every session on the server rather than just the current one. This is the form you put in `.tmux.conf` for things like `status-style`, `history-limit`, or `mouse`. Without `-g`, the option is scoped to the current session only.
// tmux command
: set -g OPTION// gotcha
Modern tmux (3.x) auto-detects an option's table, so `set -g` also sets window options like `mode-keys` — `setw` (id 69) is just the explicit alias, not a hard requirement. When you want to add to a list or style option instead of replacing it, use the append form `set -ag`; plain `set -g` overwrites the whole value.