Add check to ensure the app hook was installed, if not don't dump errors about

the function not existing

admin/inc/class.uiconfig.inc.php

@@ -215,7 +215,14 @@
 						break;
 					case 'hook':
 						$newval = ereg_replace(' ','_',$newval);
+						if(function_exists($newval))
+						{
 							$t->set_var($value,$newval($current_config));
+						}
+						else
+						{
+							$t->set_var($value,'');
+						}
 						break;
 					default:
 						$t->set_var($value,'');