What's in a empty class?

[Adam D. Ruppe via Digitalmars-d-learn]

On Tuesday, 27 October 2015 at 21:23:45 UTC, TheFlyingFiddle 
wrote:
> I can account for the first thing a vtable. But that
> should only cover 4bytes. What's in the other 4bytes?

The monitor used for `synchronized`.

(yes, this is something a lot of people want to remove as it is 
rarely all that useful yet you pay the price in all D class 
objects)