Avoid loading already registered attachments when opening a draft message (on page reload)

program/steps/mail/compose.inc

@@ -978,6 +978,11 @@ function rcmail_write_compose_attachments(&$message, $bodyIsHtml)
 {
   global $RCMAIL, $COMPOSE, $compose_mode;
 
+  $loaded_attachments = array();
+  foreach ((array)$COMPOSE['attachments'] as $id => $attachment) {
+      $loaded_attachments[$attachment['name'] . $attachment['mimetype']] = $attachment;
+  }
+
   $cid_map = $messages = array();
   foreach ((array)$message->mime_parts as $pid => $part)
   {
@@ -1005,7 +1010,8 @@ function rcmail_write_compose_attachments(&$message, $bodyIsHtml)
           }
       }
 
-      if (!$skip && ($attachment = rcmail_save_attachment($message, $pid))) {
+      if (!$skip && (($attachment = $loaded_attachments[rcmail_attachment_name($part) . $part->mimetype])
+          || ($attachment = rcmail_save_attachment($message, $pid)))) {
         $COMPOSE['attachments'][$attachment['id']] = $attachment;
         if ($bodyIsHtml && ($part->content_id || $part->content_location)) {
           $url = sprintf('%s&_id=%s&_action=display-attachment&_file=rcmfile%s',