I've been experimenting with webkit transitions with Sencha Touch, such as

-webkit-transition-property: left, top, width, height;
-webkit-transition-duration: 1s;

When I apply this css style to an object, then change the position via setPosition, it works fine, and a nice smooth transition is animated. When I try to do the same with width and height, it does nothing. The width and height are not updated at all. It also works fine for opacity, as you can see from some examples. Is there a reason why it wouldn't work with width and height or is there something else I should be doing?