With the new HUD, we see the following. What is that time? It was made at 14:28 today.
On my system that shows hh:mm:ss of rendering time. I guess you didn’t let it render for 18 hours?
The time in the HUD gets calculated from public override DateTime HudStartTime(). The Raytraced viewport implementation sets start time to UTC time of changes in render, i.e. OnRenderSizeChanged, handling of MaxPassesChanged and other updates through the change queue.
I see, I think we had some old demo code in there which was calculating the difference to 1.1.1970 
I tried returning Date.Now set in StartRenderer, but my rendering time was nearly -1 hour Using DateTime.UtcNow seems to give us the expected results. Couldn’t this be a part of the base implementation though, or is there some reason for customizing the value?
There isn’t a direct link between render engines and RealtimeDisplayMode implementations. It is something that currently implementors have to handle after a ChangeQueue has been flushed and the integrated render engine has been restarted properly.
I don’t see how this could be handled through a default implementation without introducing complicating dependencies to a render engine concept from RealtimeDisplayMode point of view.