mouse click on menu in terminal doesn't work

[Peter Eisentraut]

I'm using Emacs 24.5 from OS X Homebrew in iTerm2.

I start

    emacs -q

then run

    (xterm-mouse-mode 1)

in the scratch buffer.  Then I can use the mouse to click around in the
buffer and the mouse moves.  If I split the frame, I can also click to
switch between windows.  So Emacs can clearly see my mouse clicks.

The NEWS for Emacs 24.4 contain this item:

> ** Support for menus on text-mode terminals.
> If the terminal supports a mouse, clicking on the menu bar, or on
> sensitive portions of the mode line or header line, will drop down the
> menu defined at that position.

My understanding of this is that if I click on say "File" in the menu,
that menu opens, just like if I press F10.  But what instead happens is
that I get a *Completions* buffer in a split frame.  (I suppose this is
from the function tmm-menubar.)

Any idea why this doesn't work?