Index: src/wp-admin/js/editor-expand.js
===================================================================
--- src/wp-admin/js/editor-expand.js	(revision 30595)
+++ src/wp-admin/js/editor-expand.js	(working copy)
@@ -1008,12 +1008,6 @@
 
 				$overlay.off( 'mouseenter.focus mouseleave.focus mousemove.focus touchstart.focus' );
 
-				$editor.on( 'mouseenter.focus', function() {
-					if ( $.contains( $editor.get( 0 ), document.activeElement ) || editorHasFocus ) {
-						fadeOut();
-					}
-				} );
-
 				focusLostTimer = setTimeout( function() {
 					focusLostTimer = null;
 					$editor.off( 'mouseenter.focus' );