advanced Flex Application Development Building Rich Media X phần 7 pdf

8962CH10.qxd 11/7/07 2:04 PM Page 286 CHAPTER 10 Figure 10-13 The HSlider is now on top of the ProgressBar, because it’s wrapped in a Canvas With the HSlider now on top of the ProgressBar, it almost appears as though it were one component However, because you can see the track of the HSlider component, it is still clear there are two overlaid components To get rid of the track of the HSlider, I use CSS and an invisible image Using Fireworks, I create a 1!1 invisible PNG file (an empty 1!1 PNG file exported with transparency on) and put it in my images folder in my Flex project I embed the image as the trackSkin The MXML looks like this: