getBounds huh?

Another newbie question.
I’ve added a rectangle (testRect) movieclip to my stage.
The rectangle is placed at 200,100 and is 100 pixels across and 50 pixels tall. The stage is 800x600.

Here is my code
var b:Rectangle = getBounds(testRect);
trace (b.x, b.y,, b.bottom, b.width, b.height);

When I run it I would expect 200,100,100,200,100,50
but no, I get
-45.5 -31.5 -31.5 31.5 91 63

I added a fullscreen rectangle behind my testRect and now I get
-182 -378 -378 378 728.05 756
Double Huh?

Can someone explain what is going on?