From xemacs-m  Thu Feb 13 15:35:09 1997
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Date: Thu, 13 Feb 1997 13:33:01 -0800
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From: "William M. Perry" <wmperry@aventail.com>
To: xemacs-beta@xemacs.org
Subject: error ("Visible portion of buffer not modifiable");
Errors-to: wmperry@aventail.com
Reply-to: wmperry@aventail.com
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 [WJopW_J.WY;

What purpose does this error serve, and how can I avoid it?

-Bill P.

-Bill P.

DEFUN ("indent-to", Findent_to, 1, 3, "NIndent to column: ", /*
Indent from point with tabs and spaces until COLUMN is reached.
Optional second argument MIN says always do at least MIN spaces
 even if that goes past COLUMN; by default, MIN is zero.
If BUFFER is nil, the current buffer is assumed.
*/
       (col, minimum, buffer))
{
  /* This function can GC */
  int mincol;
  int fromcol;
  struct buffer *buf = decode_buffer (buffer, 0);
  int tab_width = XINT (buf->tab_width);
  Bufpos opoint = 0;

  CHECK_INT (col);
  if (NILP (minimum))
    minimum = Qzero;
  else
    CHECK_INT (minimum);

  XSETBUFFER (buffer, buf);
  
  fromcol = current_column (buf);
  mincol = fromcol + XINT (minimum);
  if (mincol < XINT (col)) mincol = XINT (col);

  if (fromcol == mincol)
    return make_int (mincol);

  if (tab_width <= 0 || tab_width > 1000) tab_width = 8;
  
  if (!NILP (Fextent_at (make_int (BUF_PT (buf)), buffer, Qinvisible,
			 Qnil, Qnil)))
    {
      Bufpos last_visible = last_visible_position (BUF_PT (buf), buf);

      opoint = BUF_PT (buf);
      if (last_visible >= BUF_BEGV (buf))
	BUF_SET_PT (buf, last_visible);
      else 
        error ("Visible portion of buffer not modifiable");
    }

