Ticket #39335: 39335.0.diff

src/wp-content/themes/twentyseventeen/assets/js/customize-controls.js

@@ -25 +25 @@
                 });
 
                 // Detect when the front page sections section is expanded (or closed) so we can adjust the preview accordingly.
-                wp.customize.section( 'theme_options' ).expanded.bind( function( isExpanding ) {
+                wp.customize.section( 'theme_options', function( section ) {
+                        section.expanded.bind( function( isExpanding ) {
 
-                        // Value of isExpanding will = true if you're entering the section, false if you're leaving it.
-                        wp.customize.previewer.send( 'section-highlight', { expanded: isExpanding });
-                });
+                                // Value of isExpanding will = true if you're entering the section, false if you're leaving it.
+                                wp.customize.previewer.send( 'section-highlight', { expanded: isExpanding });
+                        } );
+                } );
         });
 })( jQuery );