diff --git a/wp-includes/js/tinymce/skins/wordpress/wp-content.css b/wp-includes/js/tinymce/skins/wordpress/wp-content.css
index 2895fd9bdd..6f52773378 100644
--- a/wp-includes/js/tinymce/skins/wordpress/wp-content.css
+++ b/wp-includes/js/tinymce/skins/wordpress/wp-content.css
@@ -211,6 +211,11 @@ audio {
 	visibility: hidden;
 }
 
+/* Fix for proprietary Mozilla display attribute, see #38757 */
+[_moz_abspos] {
+	outline: none;
+}
+
 a[data-wplink-url-error],
 a[data-wplink-url-error]:hover,
 a[data-wplink-url-error]:focus {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 82a95a1a67..addb184814 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.7-beta3-39216';
+$wp_version = '4.7-beta3-39217';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.