This function is
EXPERIMENTAL. The behaviour of this function, the
name of this function, and anything else documented about this
function may change without notice in a future release of PHP.
Use this function at your own risk.
Apparently this function DOES, in fact, return a value as many of the MING examples show. It is a SWFDisplayItem. Here is an excerpt of an example that appears elsewhere in the MING docs...
$p = new SWFSprite();
$i = $p->add($s);
$p->nextFrame();
$i->rotate(15);
$p->nextFrame();