Re: "Attempt to modify read-only object" error with set-frame-configuration

[YAMAMOTO Mitsuharu]

>>>>> On Wed, 26 Dec 2007 00:28:42 -0500, Richard Stallman <address@hidden> 
>>>>> said:

> There is still a mystery why visibility's cons cell is pure

I guess the reason is:

  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.

                                     YAMAMOTO Mitsuharu
                                address@hidden