This event is fired when the component yields execution to the application.
This event is fired by TElAS2Client when the component needs to process Windows messages or give away the time slice to application.
True if AS2 client can continue or
False if blocking operation must be stopped.
Use this callback function if you wish to process all incoming messages yourself while TElAS2Client waits for synchronous server response. If this property is set to nil (null, Nothing), TElAS2Client uses its internal message loop to peek and dispatch messages.