This function had been marked as deprecated.

Legacy function used to generate a link categories checklist control.

Signature

dropdown_link_categories( $default = 0 )
default
 (int) Unused.
Default: 0

Return

(void)

Source

function dropdown_link_categories( $default = 0 ) {
	_deprecated_function( __FUNCTION__, '2.6.0', 'wp_link_category_checklist()' );
	global $link_id;
	wp_link_category_checklist( $link_id );
}
WP Trac GitHub

Link here