If I browse http://ikiwiki.info in emacs-w3m (without Javascript), I
can't do a [[search|plugins/search]]: the text field is there (so I can
enter my search request), but there seems to be no way to make
actually a search request (i.e., no button). 

(A remark on how it works now in the other browsers: 
In the more "complete"
browsers (Chromium etc.), the request is done by pressing Enter in the
text field.)