Re: Box cursor at EoL

[Dr Rainer Woitok <rainer.woitok@gmail.com>]

Stefan,

On Saturday, 2022-10-08 09:18:03 -0400, you wrote:

> ...
> > Does that mean that even though there is a way  to maintain a frame spe-
> > cific cursor appearance  there is no way  to maintain a  window specific
> > one? :-(
> 
> Exactly: both the `cursor-type` variable and the `cursor-type`
> frame-parameters are used by the redisplay code to decide how to draw
> the cursor.  But the redisplay code does not look at any
> window-parameter for that, so you can't change the cursor-shape on
> a "per window" basis :-(
> 
> Maybe it's time for `M-x report-emacs-bug` and request a new feature.

Well,  before I request  a feature more or less  only benefitting me but
turning out to require a total redesign of Emacs  I'd like to first con-
tinue this discussion here :-)

1. Am I correct in assuming that when I request to display a buffer in a
   new frame this will also create a new window in that new frame?

   If this were true, I could forget frames and just search for a way to
   make use of the  `cursor-type´ windows parameter,  because this would
   also solve the "same buffer in another frame" case.

2. Running `C-h v cursor-type´ returns

      cursor-type is a variable defined in `C source code´.

      Its value is t

      Cursor to use when this buffer is in the selected window.
      Values are interpreted as follows:

        t               use the cursor specified for the frame
        nil             don't display a cursor
        box             display a filled box cursor
        (box . SIZE)    display a filled box cursor, but make it
                        hollow if cursor is under masked image larger than
                        SIZE pixels in either dimension.
        hollow          display a hollow box cursor
        bar             display a vertical bar cursor with default width
        (bar . WIDTH)   display a vertical bar cursor with width WIDTH
        hbar            display a horizontal bar cursor with default height
        (hbar . HEIGHT) display a horizontal bar cursor with height HEIGHT
        ANYTHING ELSE   display a hollow box cursor

      WIDTH and HEIGHT can't exceed the frame’s canonical character size.

      When the buffer is displayed in a non-selected window, the
      cursor's appearance is instead controlled by the variable
      `cursor-in-non-selected-windows´.

        Automatically becomes buffer-local when set.
        You can customize this variable.
        Probably introduced at or before Emacs version 21.1.

   That clearly states that this buffer local variable  either allows to
   use no cursor,  a locally defined cursor specification  or the cursor
   specification for the frame, but nothing else.

So I'd suggest extending the above list of special values for buffer lo-
cal variable `cursor-type´ with

      frame             use the cursor specified for the frame (same as
                        t but with improved documentation value for hu-
                        man readers)
      window            use the cursor specified for the window

and to add these two additional alternatives for the value of buffer lo-
cal variable `cursor-type´ to every relevant evaluation of it.

But since buffer local variable  `cursor-type´  is defined in  `C source
code´,  there is no easy way for me to receive an impression of how much
effort this change would require.

Comments anybody?

Sincerely,
  Rainer