Hi Asper,
the problem with UDT is that they are, by their nature, fixed memory structures defined before runtime starts. In compilers they would say "UDT are defined at compile time".
That's why it is not possible to REDIM arrays inside UDT: the interpreter (or the compiler) must know the UDT size before execution.
From my point of view, I like to have as much freedom as possible and that's why I will reply to you that I will accept this request as possible implementation.
In any case consider that UDT with dynamic structures inside them will break backward compatibility with Operating System API or in general with functions that expects fixed memory structures with a fixed and known size.
In any case this implementation is not something that can be ready very soon.
Ciao
Eros