Scale9Grid doesn't work in MovieClip

I have a couple of MovieClips in swf files loaded with Loader.loadBytes. They are 10-th version, as3-enabled and have scale9Grid defined (I can see the tag DefineScaleGrid in them with SWiX). But when loaded, loader.content has scale9Grid == null (maybe it is normal?) and scaling is not 9-slice. I can't even set scale9Grid myself - any attempt is met with exception "One of the parameters is invalid". How to make 9-slice grid work开发者_如何学C?

I finally found this article to explain it all. So, in short, scale9Grid works only on DisplayObjects without children. I dug down to Shape in my clip and managed to set that grid.