When set to
true, on unix systems, for local panes, wezterm will query the
termios associated with the PTY to see whether local echo is disabled and
canonical input is enabled.
If those conditions are met, then the text cursor will be changed to a lock to give a visual cue that what you type will not be echoed to the screen.
This technique only works for local processes on unix systems, and will not work through other processes that themselves use PTYs. Most notably, this will not work with tmux or remote processes spawned via ssh.