Martin,

OK, I believe I've located the problem.  Sorry for all of the confusion.

However, this is not necessarily simple, and you will need to load more in order
to see it.  I spent a lot of time on this today, but I cannot easily simplify
things more.  I think you will need to look at it first, and then we'll see what
we can do together to focus in more on the problem.

But I suspect that just by looking at the problematic part of the code you will
be able to offer a suggestion that will fix things.  Hope so.  I call
`display-buffer' with the old calling sequence, and that, I imagine, is the
problem.  With a little luck you will be able to let me know what the correction
should be, and that will take care of things.

You might be able to do that without bothering to test at all - see the end of
this message.  But I suspect it might help you to see what happens, even so.

I have tested this with Emacs 23.3 and with your latest window.el (Emacs 24
build from 6/20).  Here is the startup.  File throw-10.el is attached.  It loads
Icicles.

runemacs.exe -Q --debug-init  -l "window-2011-06-23a-MARTIN.el" -l "throw-10.el"
-f "1on1-emacs"

(For Emacs 23, the startup is the same, but without the -l of your window.el
file.)

Once Emacs is started, you can test as before: `M-x f TAB o'.

But to see the problem you need to be in Icicle mode, so do this first: `M-x
icy-mode' (toggles the mode).  You can thus test with and without Icicle mode to
see the difference.  With Emacs 23, both in and out of Icicle mode work.  With
your code it works only when not in Icicle mode.

--

You will need to download all of the Icicles source files for the test.  The
attached file, throw-10.el, loads them all, but it also then simplifies the part
of the code that I think is leading to the problem.  So the code you actually
need to look at is, I think, quite focused.

These are the Icicles files, and the place to get them:
http://www.emacswiki.org/cgi-bin/wiki?action=index;match=%5C.(el%7Ctar)(%5C.gz)%
3F%24

icicles-mac.el
icicles-face.el
icicles-opt.el
icicles-var.el
icicles-fn.el
icicles-mcmd.el
icicles-cmd1.el
icicles-cmd2.el
icicles-mode.el
icicles.el

The code to focus on is, I believe, in test-10.el, function
`icicle-display-candidates-in-Completions'.  (This function is called a lot, in
many Icicles contexts.)

This is the part of the code that I think is problematic - marked with a
`@@@@@@@' comment:

(let ((comp-buf  (get-buffer-create "*Completions*")))
  (unless (get-buffer-window comp-buf 'visible)
    (save-selected-window
      (display-buffer comp-buf t 0) ; <== the problem, no doubt
      (deactivate-mark))))

This calls `display-buffer', but it uses the old calling sequence, which I'm
guessing is the problem.  The point of this code is just to visit display the
buffer and deactivate the mark there.

Again, sorry for the amount of work.  Hoping this will help.

Thx - Drew