What's in a empty class?

[TheFlyingFiddle via Digitalmars-d-learn]

On Tuesday, 27 October 2015 at 21:28:31 UTC, Adam D. Ruppe wrote:
> 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)

I see Thanks.