free threaded marshaler

does anyone know what it means in ATL to have the free threaded marshaler option
on when creating the ATL object wizard? in which case we shall use it?

[David L Hill]

My understanding is that this option is rarely used and can cause unpredictable results.

I think it is used when you have an object in a server that will be accessed from a client and also accessed from the server but from a different apartment. So there are two types of access - cross-process and in-process but cross-apartment. Normally both cases would use a proxy although the in-process but cross-apartment does not require it. The free threaded marshaller is able to determine between the two and use a proxy only in the cross-process.

Please read the above with caution since this is only my understanding from the reading I have done and the one time I selected this option and had all kinds of strange problems.