Ticket #19650: alwaysapplyfilters.patch

wp-admin/includes/screen.php

@@ -21 +21 @@
         static $column_headers = array();
 
         if ( ! isset( $column_headers[ $screen->id ] ) )
-                $column_headers[ $screen->id ] = apply_filters( 'manage_' . $screen->id . '_columns', array() );
+                $column_headers[ $screen->id ] = array();
+        $column_headers[ $screen->id ] = apply_filters( 'manage_' . $screen->id . '_columns', $column_headers[ $screen->id ] );
 
         return $column_headers[ $screen->id ];
 }