Index: Classes/ExtDirect/ActionHandler.php
===================================================================
--- Classes/ExtDirect/ActionHandler.php	(revision 3359)
+++ Classes/ExtDirect/ActionHandler.php	(working copy)
@@ -418,6 +418,8 @@
 					'xtype' => 'checkboxgroup',
 					'itemCls' => 'x-check-group-alt',
 					'columns' => 1,
+					'style' => 'max-height: 100px',
+					'autoScroll' => true,
 					'items' => array(
 						$this->getReceipientsOfStage($nextStageId)
 					)