opaqueBackground problem


this.createEmptyMovieClip("triangle_mc", this.getNextHighestDepth());
triangle_mc.beginFill(0x00ff00, 100);
triangle_mc.moveTo(200, 200);
triangle_mc.lineTo(300, 200);
triangle_mc.lineTo(300, 300);
triangle_mc.lineTo(200, 300);
triangle_mc.lineTo(200, 200);
triangle_mc.opaqueBackground = 0x000000;

this.createEmptyMovieClip("triangle_mc1", this.getNextHighestDepth());
triangle_mc1.cacheAsBitmap = true
triangle_mc1.beginFill(0x00ffff, 100);
triangle_mc1.moveTo(150, 150);
triangle_mc1.lineTo(250, 150);
triangle_mc1.lineTo(250, 250);
triangle_mc1.lineTo(150, 250);
triangle_mc1.lineTo(150, 150);
triangle_mc1.opaqueBackground = 0x000000;

triangle_mc1.onPress = function (){
triangle_mc1.onRelease = function (){

The above code creates two squares both with an opaqueBackground set to black and the cyan box is dragable. If you render this code you will see one box is stagered and stacked on top of the otherbox.

The problem is - look at the the cyan box and notice to the right and below there is a black outline. Also notice the green box has its lower right and bottom outlined.

Now turn off the opaqueBackground and you will see two perfectly drawn squares without any outlines.

Question, is there a way to us the opaqueBackground method without the opaqueBackground color showing?