WebSession.PrepareSession
From Xojo Documentation
Event
WebSession.PrepareSession(ByRef HTMLHeader as String)
New in 2012r1
Supported for all project types and targets.
New in 2012r1
Supported for all project types and targets.
Fires when the user's browser first connects to your web application. Changing the value of the HTMLHeader parameter will send those changes only to the current session.