From the documentation, I see that you can control which way a Dropdown expands based on the Template's pivot and anchor. I have a Dropdown positioned near the top of the canvas, and its Template is anchored to the bottom with its pivot on top. However, the Dropdown always expands upward, as shown below. This happens no matter how I position the Dropdown or its Template. Here's a hierarchy snippet. The strangest part of this is that when placed at the top, expanding the Dropdown upward actually pushes it outside of the parent Canvas. So the automatic expansion is doing the opposite of what it's supposed to.