diff -r 490d5cc509ed -r cf61fcea0001 wp/wp-includes/customize/class-wp-widget-area-customize-control.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/customize/class-wp-widget-area-customize-control.php	Mon Oct 14 17:39:30 2019 +0200
@@ -0,0 +1,66 @@
+<?php
+/**
+ * Customize API: WP_Widget_Area_Customize_Control class
+ *
+ * @package WordPress
+ * @subpackage Customize
+ * @since 3.4.0
+ */
+
+/**
+ * Widget Area Customize Control class.
+ *
+ * @since 3.9.0
+ *
+ * @see WP_Customize_Control
+ */
+class WP_Widget_Area_Customize_Control extends WP_Customize_Control {
+
+	/**
+	 * Customize control type.
+	 *
+	 * @since 3.9.0
+	 * @var string
+	 */
+	public $type = 'sidebar_widgets';
+
+	/**
+	 * Sidebar ID.
+	 *
+	 * @since 3.9.0
+	 * @var int|string
+	 */
+	public $sidebar_id;
+
+	/**
+	 * Refreshes the parameters passed to the JavaScript via JSON.
+	 *
+	 * @since 3.9.0
+	 */
+	public function to_json() {
+		parent::to_json();
+		$exported_properties = array( 'sidebar_id' );
+		foreach ( $exported_properties as $key ) {
+			$this->json[ $key ] = $this->$key;
+		}
+	}
+
+	/**
+	 * Renders the control's content.
+	 *
+	 * @since 3.9.0
+	 */
+	public function render_content() {
+		$id = 'reorder-widgets-desc-' . str_replace( array( '[', ']' ), array( '-', '' ), $this->id );
+		?>
+		<button type="button" class="button add-new-widget" aria-expanded="false" aria-controls="available-widgets">
+			<?php _e( 'Add a Widget' ); ?>
+		</button>
+		<button type="button" class="button-link reorder-toggle" aria-label="<?php esc_attr_e( 'Reorder widgets' ); ?>" aria-describedby="<?php echo esc_attr( $id ); ?>">
+			<span class="reorder"><?php _e( 'Reorder' ); ?></span>
+			<span class="reorder-done"><?php _e( 'Done' ); ?></span>
+		</button>
+		<p class="screen-reader-text" id="<?php echo esc_attr( $id ); ?>"><?php _e( 'When in reorder mode, additional controls to reorder widgets will be available in the widgets list above.' ); ?></p>
+		<?php
+	}
+}