transpose characters at beginning of minibuffer

[Roland Winkler]

In GNU Emacs 21.1.1 (i386-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2002-02-01 on tfkp12
configured using `configure  --prefix=/nfs/common --libexecdir=/nfs/common/lib 
--bindir=/nfs/common/lib/emacs/21.1/bin/i686-Linux 
--mandir=/nfs/common/share/man --infodir=/nfs/common/share/info --with-gcc 
--with-pop --with-x --with-x-toolkit=athena i386-pc-linux'
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: POSIX
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US
  locale-coding-system: iso-latin-1
  default-enable-multibyte-characters: nil

When I have a typo (transposed character) at the beginning of the
`input area' of the minibuffer, and I use a simple C-a C-t to fix
it, I get an error message saying that I cannot use transpose-chars
here. That's OK because minibuffer-prompt-properties's value is
(read-only t). But why does the first character still disappear and
is replaced by a blank, i.e., transpose-chars is somehow changing
the text in the minibuffer (in a weird way!) despite the error
message?

Kind of a related feature request: Usually transpose-chars operates
on the character point is on and the character before point. If
point is at the beginning of a buffer, a narrowed region, or
something like that, wouldn't it be most natural if transpose-chars
would operate on the character point is on and the character after
point?

Roland