9-Slice scaling not working in FB4?

Question

I just upgraded my FB3 flash project to FB4.7, and saw that my 9-slice symbols (which I exported from an FLA to a SWC) have stopped working.  That is, the whole graphic is now getting stretched. If I use the exact same SWC and the exact same code in my FB3 environemt all is well.
The code is really basic:
var spr:MyRoundedRect = new MyRoundedRect(); // MyRoundedRect comes from the FLA with 9slice scaling
spr.scaleX = 4;
spr.scaleY = 3;
addChild(spr);
Am I missing something? I this a known bug in Flex Builder 4.7?
Anyone else ever encounter this?
Right now, I feel like going back to Flex Builder 3, where the world seemed a better place.

Answer 1

I'm using Flash Builder 4.7 for a pure flash project (ie, no mxml) & all my graphics objects are in a swc that was exported from an FLA. 
I've made some progress with that issue. If I explicitly assign the scale9Grid dimensions in the code, it seems to work:
  obj.scale9Grid = new Rectangle(x,y,w,h)
...but having to do that is a real productivity killer.  Would be nice to use the 9-slice guide setting in the FLA