Address dynamic class property deprecation warnings

templates/DummyBox.php

@@ -8,6 +8,10 @@
 
 class DummyBox extends SubTemplate
 {
+	private $_class;
+	private $_content;
+	private $_title;
+
 	public function __construct($title = '', $content = '', $class = '')
 	{
 		$this->_title = $title;