Re: highlight failed part of isearch input

["Robert J. Chassell" <bob@rattlesnake.com>]

    When you search for such a string, Emacs does not let you simply
    use `DEL' to back out the failure part, character by character ...

I do not understand.  

To back out of a failure, invoke isearch-del-char (`C-M-w').  That
deletes one character from the end of the search string and searches
again.

    When you search for such a string, Emacs does not let you simply
    use `DEL' to back out the failure part, character by character;
    hitting `DEL' removes the entire search string at once.

isearch-delete-char (`DEL') only removes the entire search string if
you use isearch-yank-word-or-char (`C-w') and only if you also make
that word be the only part of the search string.  If you invoke
isearch-yank-word-or-char (`C-w') twice, isearch-delete-char (`DEL')
removes only the last.

You can use isearch-yank-word-or-char (`C-w') to gather a complete
word and then remove characters from that string with isearch-del-char
(`C-M-w').

-- 
    Robert J. Chassell                          GnuPG Key ID: 004B4AC8
    bob@rattlesnake.com                         bob@gnu.org
    http://www.rattlesnake.com                  http://www.teak.cc