Profiles

Mentioned in [28884] on Core SVN:
After [28883], `remove_filter()` should set `$GLOBALS['wp_filter'][ $tag ]` to `array()` when empty.

Created ticket #28142 on Core Trac:
removing all callbacks from an action results in NULL callback

Created ticket #24680 on Core Trac:
wp_dropdown_users references user_login attribute that is never set

Reopened ticket #12702 on Core Trac:
Enable sticky post checkbox for custom post type Publish metabox