# tmux.Session.ActiveWindowIndex

- **Module:** tmux.Session
- **Package:** github.com/libtmux/libtmux-go/tmux
- **Language:** Go
- **Kind:** method
- **Source:** https://github.com/libtmux/libtmux-go/blob/5f808882015a975a65acc7f9da5b3ff0d5cbdc91/tmux/format_generated.go#L822
- **Page:** https://libtmux.org/reference/go/tmux-session-activewindowindex/

```
tmux.Session.ActiveWindowIndex() -> (int, bool)
```

ActiveWindowIndex returns tmux #{active_window_index} as int from this Session's materialized session-scoped fields (tmux 3.2a or later).