select-frame-set-input-focus mystery

[David Reitter]

While producing a fix for the pop-to-buffer problem, I encountered  
this strange behavior. Can somebody please explain what's happening,  
or check if this is a bug?

The following code should select frame f1 and set input focus to it.  
(Open a second frame and keep it partially over the first one to  
reproduce.)

(let ((f1 (car (frame-list)))
      (f2 (car (cdr (frame-list)))))

  (print f2)
  (select-frame-set-input-focus f2)
  (print f1)
  (select-frame-set-input-focus f1))


However, in my Emacs build (current CVS Emacs, Carbon port) it will  
leave f1 raised, but set input focus to f2.

Additionally, if you want to select f2 with a mouse click (into the  
single window shown), it will NOT be selected!

However, the following will work just fine:

(let ((f1 (car (frame-list)))
      (f2 (car (cdr (frame-list)))))

  (print f2)
  (select-frame-set-input-focus f2)
  (print f1)
  (message "test")
  (select-frame-set-input-focus f1))

Note that all I've done was to insert a `message' command.

The documentation of `select-frame' says that the window manager may  
select another frame upon returning to the main event loop.
However, one would expect that `select-frame-set-input-focus' sets  
the input focus in a way that actually works in all circumstances,  
right?