For a global search, the result of custom command `g' seems to work, while the custom command `f' fails. I am guessing this has to do with `search' block is not tied in strongly to the greater set of custom command tools, but wanted to bring it to your attention in case it was found to be unwanted behavior.
#+BEGIN_SRC emacs-lisp (setq org-agenda-custom-commands '(("g" "Global search" ((search "."))) ("f" "Global search after tag filter" ((search ".")) ((org-agenda-tag-filter-preset '("+work")))))) #+END_SRC In other words, the regexp wildcard `.' works with `(search ".")' alone, but seems to fail after a tag-filter, i.e. only headlines with periods in them work. -- Brady