WordPress at a glance
action is not described

welcome_panel action-hook . WP 3.5.0

Add content to the welcome panel on the admin dashboard.

To remove the default welcome panel, use remove_action():

remove_action( 'welcome_panel', 'wp_welcome_panel' );

Usage

add_action( 'welcome_panel', 'action_function_name_4900' );
function action_function_name_4900(){
	// action...
}

Where the hook is called

In file: /wp-admin/index.php
welcome_panel
wp-admin/index.php 142
do_action( 'welcome_panel' );

Where the hook is used (in WP core)

wp-includes/default-filters.php 360
add_action( 'welcome_panel', 'wp_welcome_panel' );