Hide and Show buttons in the DC toolbar based on preview mode

You can customize the visibility of your newly added button by overriding the actionVisible(extraParams:Object=null):Boolean method in CCRCustomActionHandler class. This sample restricts the visibility of button when the letter is opened in Preview mode.

override public function actionVisible(extraParams:Object=null):Boolean 
{ 
           //Show the added button only when Letter is opened in Non-Preview mode. 
       return (invokeParams && !invokeParams.preview); 
}