Callback function that will be invoked on message events.
Message listeners can be added with hwc.addMessageListener.
<static> MessageListener( flag, msgId )
| Name | Type | Description |
| flag | number | A number indicating which message event occured (will be one of hwc.MSG_ADDED, hwc.MSG_REMOVED, hwc.MSG_UPDATED, hwc.MSG_REFRESH). |
| msgId | number | The message id of the affected message. |