Simple way to get a progress bar is to draw two rectangles, one inside the other. Make them the same size (copy and paste) or make the inside one slightly smaller if you want a border. Make the inside one a solid color and setup it's Horizontal Size (width) control engine attribute so that it changes it's width. Don't forget to set the anchor to the left.
This works good for drawing tanks with fluid level too, just set the height attribute instead.