// demoing by sticking all the available values onto node_content
$items['content_type'] =
array(
'title' =>
t('Node content'),
'weight' => -10,
'single' => TRUE, // only provides a single content type
'content_types' => 'panels_admin_content_types_node_content',
'render callback' => 'panels_content_node_content',
'add callback' => 'panels_admin_edit_node_content',
'edit callback' => 'panels_admin_edit_node_content',
'title callback' => 'panels_admin_title_node_content', // all the new ones follow
'visibility control' => 'panels_admin_visibility_control_node_content',
'visibility submit' => 'panels_admin_visibility_submit_node_content',
'visibility render' => 'panels_content_visibility_node_content',
'visibility serialize' => TRUE,
'ignore roles' => FALSE,
'roles and visibility' => TRUE,
'form control' => 'panels_admin_form_control_node_content',
);