For some not known reason screensaver lock with password do not work.
…seems, actualy work, only settings time for it is in adition for time to start screensaver.
Minimum time to lock screen 30 s, its to big, to instantly lock screen by starting screensaver with mouse cursor. This can be fixed, and no need for additional softaware for locking screen.
And now it is another bad thing, that you can not set shorter time to lock sreen on screensaver than time to start screensaver, and timing to lock screen adding to time of start screensaver.
…I think, screensavers lock screen can have option “lock screen at system boot” (or something), in that way it will be possible lock boot Haiku system with password.