vga

workaround
WordPress 4.3

add_menu_page('Custom Menu','Custom Menu','edit_sample_cpt','custom_menu','sample_display_function','dashicons-arrow-right',48);

add_submenu_page('edit.php?post_type=sample_cpt,'Add New','Add New','edit_sample_cpt','post-new.php?post_type=sample_cpt);