input: [Category] Concurrency Management [Description] When callbacks enter the client, they do so on a worker thread. If the callback object is a Windows Forms object, that worker thread cannot access the form directly, and instead, the call must be marshaled to the UI thread. Fortunately, WCF can do that automatically for you. Simply call the proxy on the UI thread, and the callback will be marshaled to the UI thread in turn. The download demonstrates this behavior. [Last Updated] 9/7/2006 [Title] 
output: Windows Forms and Callbacks