A custom windows form control named 'tweet' is in a dll. The custom control has couple of basic controls to display a tweet. I add this custom control to my main application. This custom control has a button named "retweet", when some user clicks this "retweet" button, i need to send some message to the main application. Unfortunately the this tweet control has no idea about this main application (both or in their own namespaces) How can i send messages from this custom control to the main application?