Ticket #23911: 23911.2.patch

wp-admin/js/post-formats.js

@@ -11 +11 @@
         $(function(){
                 var $container = $( '.post-formats-fields' );
 
+                $('.post-format-tip').html( $('[data-wp-format="' + postFormats.currentPostFormat + '"]').prop('title') );
+
                 // Post formats selection
                 $('.post-format-options').on( 'click', 'a', function(e){
                         e.preventDefault();