agrogeek

/* actions fired when listing/adding/editing posts or pages */
/* admin_head-(hookname) to head include */
/* admin_footer-(hookname) to footer include */
add_action( 'admin_head-post.php', 'admin_head_post_editing' );
add_action( 'admin_head-post-new.php',  'admin_head_post_new' );
add_action( 'admin_head-edit.php', 'admin_head_post_listing' );

function admin_head_post_editing() {
	echo 'you are editing a post';
}

agrogeek

<?php

wp_dropdown_categories( array(
	'taxonomy'   => 'category',
	'multiple'   => true,
	'walker'     => new Willy_Walker_CategoryDropdown(),
	'selected'   => array( 10, 12 ), // selected terms…
	'hide_empty' => false,
) );