MI, FrameDecorator.frame_args () and variable objects

Hi, 

I bumped into another issue. I have custom frame decorator
that adds "synthetic" arguments in the same sense as described
in documentation [1]. 

It works fine, the problem is how to get a variable object for
such a "synthethic" argument to inspect "contents" of this
argument. For example, assume the argument is a pointer to 
a structure and I need to check the contents of it. 
Is there a way to get such a variable object? Or any other way
to achieve effectively the same thing?

Looking at the code of mi_cmd_var_create() it seems to me that
this is currently impossible but I might be missing something. 

Best, Jan

[1]: https://sourceware.org/gdb/onlinedocs/gdb/Frame-Decorator-API.html