If you 

 * Add a link to a non-existant page and save. (e.g. [[somewhere-over-the-rainbow]])
 * Click the question mark to create the page.
 * Click the cancel button.

You get a 404 as the page doesn't exist. This patch redirects to the from location
if it is known.


        === modified file 'IkiWiki/CGI.pm'
        --- IkiWiki/CGI.pm
        +++ IkiWiki/CGI.pm
        @@ -427,7 +427,11 @@
                }
        
                if ($form->submitted eq "Cancel") {
        -               redirect($q, "$config{url}/".htmlpage($page));
        +               if ( $newpage && defined $from ) {
        +                       redirect($q, "$config{url}/".htmlpage($from));
        +               } else {
        +                       redirect($q, "$config{url}/".htmlpage($page));
        +               }
                        return;
                }
                elsif ($form->submitted eq "Preview") {



[P.S. just above that is 

                $type=$form->param('type');
                if (defined $type && length $type && $hooks{htmlize}{$type}) {
                        $type=possibly_foolish_untaint($type);
                }
                ....
                $file=$page.".".$type;

I'm a little worried by the `possibly_foolish_untaint` (good name for it by the way,
makes it stick out). I don't think much can be done to exploit this (if anything), 
but it seems like you could have a very strict regex there rather than the untaint,
is there aren't going to be many possible extensions. Something like `/(.\w+)+/`
(groups of dot separated alpha-num chars if my perl-foo isn't failing me). You could
at least exclude `/` and `..`. I'm happy to turn this in to a patch if you agree.]