Boolean word/regexp search problem

[Matt Lundin <mdl@imapmail.org>]

The word/regexp agenda search to work with more than one word or regexp
unless the first word or regexp is also preceded by a "+" or "-".

Take the following example.

--8<---------------cut here---------------start------------->8---
* Org-mode

Org mode is a major mode for Emacs written by Carsten Dominik.
--8<---------------cut here---------------end--------------->8---

Let's say I search for Emacs with "C-a s [RET] Emacs". So far, so good:
this item appears in the results. But let's say I want to narrow down
the search. When I press "[" to add a search term, I see the following
prompt in the minibuffer:

[+-]Word/{Regexp} ...: Emacs +

If I complete the prompt as given ("Emacs +Carsten"), there are no
results.

The search only succeeds if I add a "+" in front of Emacs as well, i.e.,
"+Emacs +Carsten". 

The same behavior occurs with exclusion ("-") and with the regexp
search (i.e., brackets).

Two questions:

1) Do boolean word/regexp searches require a "+" or "-" symbol before
the first word/regexp? If so, this is a bit confusing, since tag and
property searches do not require an initial symbol. (E.g.,
"emacs+orgmode" works as a tag search.)

2) If boolean word/regexp do require an initial "+" or "-", could the
prompt after pressing "[" or "]" or "{" or "}" in the search results
buffer be amended to add a plus in front of the first search term?

Here is the relevant portion of the manual:

,----[10.5 Commands in the agenda buffer]
| `[ ] { }'
| 
|     in search view
|           add new search words (`[' and `]') or new regular expressions
|           (`{' and `}') to the query string.  The opening bracket/brace
|           will add a positive search term prefixed by `+', indicating
|           that this search term must occur/match in the entry.  The
|           closing bracket/brace will add a negative search term which
|           must not occur/match in the entry for it to be selected.
`----

Thanks,
Matt