RE: ibuffer problem with pop-up-frames non-nil

[Drew Adams]

[speaking of get-window-buffer second argument]

    > Yes, `0' is better.
    > I would even prefer `t',

    Maybe here it makes sense.  But be super extra careful with t in
    such places: it considers all frames including frames on other displays.

I didn't know that. Is that behavior special for `t'? Wouldn't it logically
apply to `visible' and `0' also?

If not:

 - Why is `t' an exception in this regard?
 - Is there no way to get the invisible-frames-too behavior
   of `t', without also the other-displays-too behavior?

What about other functions that have similar FRAME argument values (nil, t,
0, some-frame)? Do they have similar behavior?

Is this documented? The doc string doesn't say anything about it - shouldn't
it?