>   1. w32-win.el has a literal cons-cell in the following function:
 >
 >     (defun x-handle-iconic (switch)
 >       "Make \"-iconic\" SWITCH apply only to the initial frame."
 >       (push '(visibility . icon) initial-frame-alist))
 >
 >      Note that x-win.el also has an equivalent one.
 >
 >   2. On the multi-tty merge, term/*-win.elc files are changed to be
 >      preloaded.  As a result, the above cons cell is allocated in the
 >      pure storage on Emacs 23.
 >
 >   3. The X11 version of Fx_create_frame creates a copy of frame
 >      parameters,
 >
 >       3030	DEFUN ("x-create-frame", Fx_create_frame, Sx_create_frame,
 >        :
 >       3057	  parms = Fcopy_alist (parms);
 >
 >      but the W32 port doesn't do so.
 >
 > You don't see the problem on Emacs 22 or on X11 because of 2 or 3
 > above, respectively.
 >
 > As for 3 above, the Carbon port of Emacs 22 creates a copy of frame
 > parameters just as in X11.  But it seems to be changed not to do so on
 > the multi-tty merge for some reason I'm not sure.

Confirmed :-)

The simple patch I attached handles all problems I encountered in this
context, including the pure storage problems and that of multiple
occurrences of fringes I mentioned earlier.