diff -r 490d5cc509ed -r cf61fcea0001 wp/wp-admin/press-this.php
--- a/wp/wp-admin/press-this.php	Tue Jun 09 11:14:17 2015 +0000
+++ b/wp/wp-admin/press-this.php	Mon Oct 14 17:39:30 2019 +0200
@@ -6,16 +6,70 @@
  * @subpackage Press_This
  */
 
-define('IFRAME_REQUEST' , true);
+define( 'IFRAME_REQUEST' , true );
 
 /** WordPress Administration Bootstrap */
 require_once( dirname( __FILE__ ) . '/admin.php' );
 
-if ( ! current_user_can( 'edit_posts' ) || ! current_user_can( get_post_type_object( 'post' )->cap->create_posts ) )
-	wp_die( __( 'Cheatin’ uh?' ), 403 );
+function wp_load_press_this() {
+	$plugin_slug = 'press-this';
+	$plugin_file = 'press-this/press-this-plugin.php';
 
-if ( empty( $GLOBALS['wp_press_this'] ) ) {
-	include( ABSPATH . 'wp-admin/includes/class-wp-press-this.php' );
+	if ( ! current_user_can( 'edit_posts' ) || ! current_user_can( get_post_type_object( 'post' )->cap->create_posts ) ) {
+		wp_die(
+			__( 'Sorry, you are not allowed to create posts as this user.' ),
+			__( 'You need a higher level of permission.' ),
+			403
+		);
+	} elseif ( is_plugin_active( $plugin_file ) ) {
+		include( WP_PLUGIN_DIR . '/press-this/class-wp-press-this-plugin.php' );
+		$wp_press_this = new WP_Press_This_Plugin();
+		$wp_press_this->html();
+	} elseif ( current_user_can( 'activate_plugins' ) ) {
+		if ( file_exists( WP_PLUGIN_DIR . '/' . $plugin_file ) ) {
+			$url = wp_nonce_url( add_query_arg( array(
+				'action' => 'activate',
+				'plugin' => $plugin_file,
+				'from'   => 'press-this',
+			), admin_url( 'plugins.php' ) ), 'activate-plugin_' . $plugin_file );
+			$action = sprintf(
+				'<a href="%1$s" aria-label="%2$s">%2$s</a>',
+				esc_url( $url ),
+				__( 'Activate Press This' )
+			);
+		} else {
+			if ( is_main_site() ) {
+				$url = wp_nonce_url( add_query_arg( array(
+					'action' => 'install-plugin',
+					'plugin' => $plugin_slug,
+					'from'   => 'press-this',
+				), self_admin_url( 'update.php' ) ), 'install-plugin_' . $plugin_slug );
+				$action = sprintf(
+					'<a href="%1$s" class="install-now" data-slug="%2$s" data-name="%2$s" aria-label="%3$s">%3$s</a>',
+					esc_url( $url ),
+					esc_attr( $plugin_slug ),
+					__( 'Install Now' )
+				);
+			} else {
+				$action = sprintf(
+					/* translators: URL to wp-admin/press-this.php */
+					__( 'Press This is not installed. Please install Press This from <a href="%s">the main site</a>.' ),
+					get_admin_url( get_current_network_id(), 'press-this.php' )
+				);
+			}
+		}
+		wp_die(
+			__( 'The Press This plugin is required.' ) . '<br />' . $action,
+			__( 'Installation Required' ),
+			200
+		);
+	} else {
+		wp_die(
+			__( 'Press This is not available. Please contact your site administrator.' ),
+			__( 'Installation Required' ),
+			200
+		);
+	}
 }
 
-$GLOBALS['wp_press_this']->html();
+wp_load_press_this();