For TNVT hosts, changes are sent to the FVTerm browser as they are received from the host in a "send changes only" manner. In many cases there is no way to determine if a screen is "new" or is just being updated. Internally up to 100 unique changes can be sent without it looking like a "new screen".
The historySaveSize acts as a determinator--any change stream that is equal to or greater than this value indicates to the history logic to "treat this as a new screen".
