dynamic-extent arrays - can I specify element-type?

Hi LispWorkers,

>From consulting the documentation on optimizing code it seems that only arrays
specifically resulting from calls to (make-array n) or (make-array n
:initial-element x) can be declared to have dynamic extent. So declaring an
array created by (make-array n :initial-element x :element-type '(unsigned-byte
8)) to have only dynamic scope would be pointless? In
examples/opengl/openglvectors.lisp, however, the macro opengl:with-gl-vectors
seems to allow dynamic allocation of arrays with both element-type and
initial-contents fully specified - though these are also static arrays. So is
it, in fact, possible to be more specific in this situation? Perhaps so long as
the objects (as long as they live) are allocated in foreign space?

Best,
Chris