*   case changes could be completed.
     */
    private boolean viChangeCase(int count) throws IOException {
        boolean ok = true;
        for (int i = 0; ok && i < count; i++) {

            ok = buf.cursor < buf.buffer.length ();
            if (ok) {
                char ch = buf.buffer.charAt(buf.cursor);
                if (Character.isUpperCase(ch)) {
                    ch = Character.toLowerCase(ch);
                }
                else if (Character.isLowerCase(ch)) {
                    ch = Character.toUpperCase(ch);
                }
                buf.buffer.setCharAt(buf.cursor, ch);
                drawBuffer(1);
                moveCursor(1);
            }
        }
        return ok;
    }