Based on the design, I found that Flash CS4’s Slider component is too thin — it needs to be thicker, i.e. I have to change the Slider’s height. I checked the API docs, and there’s nothing for setting the SliderTrackSkin’s height. Looks like I’ll have to dig into the UI components myself. Exploration… Result: In Flash CS4, the UI component files are under [X:\**]\Adobe Flash CS4\Common\Configuration\Components, and the source files are under [X:\**]\Adobe Flash CS4\Common\Configuration\Component Source\ActionScript 3.0\User Interface