#539022 by dropcube: Use current theme during Batch API processes.

includes/form.inc

@@ -2890,6 +2890,8 @@ function batch_set($batch_definition) {
 function batch_process($redirect = NULL, $url = NULL) {
   $batch =& batch_get();
 
+  drupal_theme_initialize();
+  
   if (isset($batch)) {
     // Add process information
     $url = isset($url) ? $url : 'batch';
@@ -2899,6 +2901,7 @@ function batch_process($redirect = NULL, $url = NULL) {
       'url' => isset($url) ? $url : 'batch',
       'source_page' => $_GET['q'],
       'redirect' => $redirect,
+      'theme' => $GLOBALS['theme_key'],
     );
     $batch += $process_info;
 

modules/system/system.admin.inc

@@ -1928,6 +1928,11 @@ function system_php() {
 function system_batch_page() {
   require_once DRUPAL_ROOT . '/includes/batch.inc';
   $output = _batch_page();
+  
+  // Use the same theme that the page that started the batch.
+  $batch = &batch_get();
+  $GLOBALS['custom_theme'] = $batch['theme'];
+
   if ($output === FALSE) {
     drupal_access_denied();
   }