Re: [Emacs-diffs] trunk r115434: * subr.el (read-passwd): Disable show-paren-mode.

[martin rudalics <rudalics@gmx.at>]

 > I don't see why we should write it in C, but stripping away overlays and
 > text-properties would make sense.

In Lisp there's always a simple way to inadvertently or maliciously
reveal some text property.  C wouldn't eliminate but reduce that danger.

 > Another approach would be to replace
 > chars with . not just in the display but in the buffer itself and keep
 > the actual chars in a text property.

Sounds good but not entirely trivial to implement.

 > The main property I want to
 > preserve is that normal editing works (tho you have to do it "blind"),
 > which is why the "hiding" is done in an after-change-function.

Which is the weak point IMO.  I wouldn't like to type a password with
`after-change-functions' or any other hook running in between.
Obviously, if the text is in a (mini-)buffer there's always a way that
redisplay reveals it.  In this sense `show-paren-mode' was only the tip
of the iceberg.  I would like a "hide" text property which can be only
set and removed from C and overrides any other text or overlay property
specified anywhere else.

martin