The headers stored for cached pages ended in a newline, which caused header("") to get called when serving the page.
On some PHP versions (happens on 4.3.3 at least, but not in 5.0), PHP adds a blank header to the HTTP request (i.e. just \r\n) which ends HTTP headers prematurely and adds a newline at the beginning of the page.
This was not an issue before because we output HTML. Now that we have GZip compression, this bug caused corruption of the output. :P
*phew*
* The _validate hook and the _nodeapi('validate') hook of the node API (1) no longer take an 'error' parameter and (2) should no longer return an error array. To set an error, call form_set_error().
* The _form hook of the node module no longer takes a form hook and should not worry about displaying errors. Ditto for _nodeapi('form_post') and _nodeapi('form_pre').
CHANGES
-------
+ Introduced tabs. First, we extended the menu system to support tabs. Next, a tab was added for every link that was (1) an administrative action other than the implicit 'view' (2) relevant to that particular page only. This is illustrated by the fact that all tabs are verbs and that clicking a page's tab leads you to a subpage of that page.
+ Flattened the administration menu. The tabs helped simplify the navigation menu as I could separate 'actions' from 'navigation'. In addition, I removed the 'administer > configuration'-menu, renamed 'blocks' to 'sidebars' which I hope is a bit more descriptive, and made a couple more changes. Earlier, we already renamed 'taxonomy' to 'categorization' and we move 'statistics' under 'logs'.
+ Grouped settings. All settings have been grouped under 'administer > settings'.
TODO
----
+ Update core themes: only Xtemplate default supports tabs and even those look ugly. Need help.
+ Update contributed modules. The menu() hook changed drastically. Updating your code adhere the new menu() function should be 90% of the work. Moreover, ensure that your modue's admin links are still valid and that URLs to node get updated to the new scheme ('node/view/x' -> 'node/x').
+ Introduced two new functions:
1. form_set_error($name, $message): files an error against the form
element with the specified $name.
2. form_has_errors(): returns true if errors has been filed against
form elements.
+ Updated the form handling:
1. The form_ functions will add 'class="error"' when a form field
has been found to be erroneous.
2. The error message is passed to theme_form_element() when the
particular form field has been found to be erroneous.
+ I updated the user and profile module to take advantage of these new
functions.
+ IMPORTANT: the _user() hook changed. The 'validate' case should no
longer retun an error message when something goes wrong but should
set it with form_set_error().
administrators will be able to define a custom 403 page, just as they
can define 404 pages now.
This needs to be documented in the "Changes since / migrating to ..."
pages.
Dries Buytaert
Steven Wittens
Kjartan Mannes