diff -urN ../thunderbird_labels.orig/thunderbird_labels.php ./thunderbird_labels.php
--- ../thunderbird_labels.orig/thunderbird_labels.php	2014-05-18 22:47:26.000000000 +0300
+++ ./thunderbird_labels.php	2015-09-29 03:08:39.000000000 +0300
@@ -363,6 +363,7 @@
 	
 	function tb_label_popup()
 	{
+if (!defined('GUI_OBJECT_TB_LABEL_POPUP_OBJ_ADDED')) {
 	  $custom_labels = $this->rc->config->get('tb_label_custom_labels');
 		$out = '<div id="tb_label_popup" class="popupmenu">
 			<ul class="toolbarmenu">';
@@ -374,7 +375,9 @@
 		$out .= '</ul>
 		</div>';
 		$this->rc->output->add_gui_object('tb_label_popup_obj', 'tb_label_popup');
+define('GUI_OBJECT_TB_LABEL_POPUP_OBJ_ADDED', true);
     	$this->rc->output->add_footer($out);
+}
 	}
 }