This is a nasty new requirement, discovered as an aside while looking
into ways to resolve the ''crucial mismatch'' between the `OutputSlot`
and `BufferProvider`, using the proxy-implementation of `BufferProvider`
(thereby expanding on the recent draft with the `BufferProxyAdaptor`)
The point is, if the BufferMetadata will be used beyond the internal coordination
within BufferProvider, then it will be used as part of actual buffer storage.
And this implies that the actual size of the allocation may differ (be greater)
than the nominally required size (since we'll very likely employ some kind
of memory tiling, for reasons of performance).
This leads again to an analysis of `BufferMetadata` usage,
with the conclusion to add the actual storage size directly into the API,
but treat it as an ''extra'' and not integrated into the ''buffer type''
Phew ... quite complex alltogether
Ichthyostega
ea0ae5f78e