Returns from a dialog raised by a {@link org.apache.myfaces.trinidad.component.UIXCommand UIXCommand} component,or any component implementing {@link org.apache.myfaces.trinidad.component.DialogSource DialogSource}, or any direct calls to {@link #launchDialog launchDialog()}.
@see org.apache.myfaces.trinidad.event.ReturnEvent
@param returnValue the value to be delivered in the the ReturnEvent
@todo Do I need an explicit "cancelled" concept, oris a null returnValue good enough?