source: sipes/modules_contrib/panels/D6UPDATE.txt @ 4f375e3

CHANGES DURING D6 UPDATE TO PANELS 3

ALL PLUGINS
===========

Function to advertise directory for plugins:
  hook_ctools_plugin_directory($module, $plugin)

LAYOUTS
=======

All layouts should use templates
'icon' now uses the defined path and should no longer have path built in.
'css' now uses defined path and should no longer have path built in.
DOCUMENTATION NOTE: You can just copy any layout css file directly to your theme. It should no longer be in theme/layouts directory.
administrative view of a layout can now have its own theme function.

CONTENT TYPES
=============

panels_node_legacy module renamed to panels_node_content.module
-- NEED UPDATE TO RENAME IN SYSTEM TABLE.

'title callback' now has $subtype as the first argument.
'render' now has $subtype as the first argument.
'content_types' now 'content types'.
New 'content type' to fetch information a single content type so we don't have
to load all of them all the time.
New 'defaults' array in either the type or subtype declaration to provide
defaults for the add form.

CONTEXTS
========

Function signature on submit and validate handlers now: ($form, &$form_values, &$form_state)
Moved to CTOOLS

RELATIONSHIPS
========

Function signature on submit and validate handlers now: ($form, &$form_values, &$form_state)
Moved to CTOOLS

ARGUMENTS
========

Function signature on submit and validate handlers now: ($form, &$form_values, &$form_state)
Moved to CTOOLS

When argument plugins fail to load a context at runtime, they must now return
error codes instead of FALSE or NULL (previously the practice). The error codes,
and their respective documentation, can be found at the top of panels.module.