RFC: change to XO sleep behavior

[Paul Fox]

recent releases of XO-1.5 (and also of F11-on-XO1, if we can ever
get suspend/resume working properly again) have a new default
behavior with regard to idle suspend.  i'm soliciting opinions on
how to fine-tune this new behavior.

before:
    in the past on XO-1, the screen would dim, and after a
    certain duration of inactivity, the laptop would suspend
    (with the screen dimmed).  a keystroke or touchpad gesture
    would waken the laptop from this state.  in contrast, pushing
    the power button would cause the screen to blank and the
    laptop to go to sleep.  one could leave this state only by
    pushing the power button again (or by closing/opening the lid).

    note that there was no ambiguity as to whether keyboard input
    would cause the laptop to wake up:  if the screen was on, it
    would, otherwise, it wouldn't.

now:
    in the new scheme, the idle sequence has changed:  after a
    fairly brief period of inactivity, the system will suspend,
    leaving the screen on.  (the user may not even know this has
    happened.)  assuming there is still no keyboard activity, a
    little later the screen will dim, and sometime after that,
    the screen will blank.  (if you care about these timings, please
    comment on #10034, rather than here.)

    now we finally come to the fine-tuning:

    a) currently, once the screen blanks, a keystroke will _not_
    wake the laptop.  as a design, it seemed to make sense that
    if the screen was off, and the power LED was flashing slowly,
    then however we got there (i.e., via power button or
    idleness), the laptop should behave the same.

    b) but having been using the laptop this way for a while,
    several people have requested that if the screen blanks due
    to idleness, that it should remain wakeable with user
    activity.  this makes it feel a lot more like a traditional
    screen saver (but note that your waking keystroke will be
    used, not dropped).  everyone seems to be agreed that the
    power button, like a lid closure, should result in a state
    where the keyboard won't wake the laptop.

    so, what do you think?  'a' or 'b'?  (note that 'a' and 'b'
    are identical with respect to power consumption.)
    
    further, if you choose 'a':  are you comfortable having two
    laptop states:
        - dark screen wakeable from keyboard
        - dark screen _not_ wakeable from keyboard
    that are visually indistinguishable?  is it worth adding yet
    another LED blink behavior to differentiate these states?

paul
=---------------------
 paul fox, pgf at laptop.org