diff -r 490d5cc509ed -r cf61fcea0001 wp/wp-includes/customize/class-wp-customize-themes-panel.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/customize/class-wp-customize-themes-panel.php	Mon Oct 14 17:39:30 2019 +0200
@@ -0,0 +1,101 @@
+<?php
+/**
+ * Customize API: WP_Customize_Themes_Panel class
+ *
+ * @package WordPress
+ * @subpackage Customize
+ * @since 4.9.0
+ */
+
+/**
+ * Customize Themes Panel Class
+ *
+ * @since 4.9.0
+ *
+ * @see WP_Customize_Panel
+ */
+class WP_Customize_Themes_Panel extends WP_Customize_Panel {
+
+	/**
+	 * Panel type.
+	 *
+	 * @since 4.9.0
+	 * @var string
+	 */
+	public $type = 'themes';
+
+	/**
+	 * An Underscore (JS) template for rendering this panel's container.
+	 *
+	 * The themes panel renders a custom panel heading with the current theme and a switch themes button.
+	 *
+	 * @see WP_Customize_Panel::print_template()
+	 *
+	 * @since 4.9.0
+	 */
+	protected function render_template() {
+		?>
+		<li id="accordion-section-{{ data.id }}" class="accordion-section control-panel-themes">
+			<h3 class="accordion-section-title">
+				<?php
+				if ( $this->manager->is_theme_active() ) {
+					echo '<span class="customize-action">' . __( 'Active theme' ) . '</span> {{ data.title }}';
+				} else {
+					echo '<span class="customize-action">' . __( 'Previewing theme' ) . '</span> {{ data.title }}';
+				}
+				?>
+
+				<?php if ( current_user_can( 'switch_themes' ) ) : ?>
+					<button type="button" class="button change-theme" aria-label="<?php esc_attr_e( 'Change theme' ); ?>"><?php _ex( 'Change', 'theme' ); ?></button>
+				<?php endif; ?>
+			</h3>
+			<ul class="accordion-sub-container control-panel-content"></ul>
+		</li>
+		<?php
+	}
+
+	/**
+	 * An Underscore (JS) template for this panel's content (but not its container).
+	 *
+	 * Class variables for this panel class are available in the `data` JS object;
+	 * export custom variables by overriding WP_Customize_Panel::json().
+	 *
+	 * @since 4.9.0
+	 *
+	 * @see WP_Customize_Panel::print_template()
+	 */
+	protected function content_template() {
+		?>
+		<li class="panel-meta customize-info accordion-section <# if ( ! data.description ) { #> cannot-expand<# } #>">
+			<button class="customize-panel-back" tabindex="-1" type="button"><span class="screen-reader-text"><?php _e( 'Back' ); ?></span></button>
+			<div class="accordion-section-title">
+				<span class="preview-notice">
+					<?php
+					/* translators: %s: themes panel title in the Customizer */
+					echo sprintf( __( 'You are browsing %s' ), '<strong class="panel-title">' . __( 'Themes' ) . '</strong>' ); // Separate strings for consistency with other panels.
+					?>
+				</span>
+				<?php if ( current_user_can( 'install_themes' ) && ! is_multisite() ) : ?>
+					<# if ( data.description ) { #>
+						<button class="customize-help-toggle dashicons dashicons-editor-help" type="button" aria-expanded="false"><span class="screen-reader-text"><?php _e( 'Help' ); ?></span></button>
+					<# } #>
+				<?php endif; ?>
+			</div>
+			<?php if ( current_user_can( 'install_themes' ) && ! is_multisite() ) : ?>
+				<# if ( data.description ) { #>
+					<div class="description customize-panel-description">
+						{{{ data.description }}}
+					</div>
+				<# } #>
+			<?php endif; ?>
+
+			<div class="customize-control-notifications-container"></div>
+		</li>
+		<li class="customize-themes-full-container-container">
+			<div class="customize-themes-full-container">
+				<div class="customize-themes-notifications"></div>
+			</div>
+		</li>
+		<?php
+	}
+}