Gradient Background for Box via CSS

.gradientStyle {
borderStyle: applicationControlBar;
fillColors: #FF0000, #0000FF;
fillAlphas: 1, 1;
highlightAlphas: 0, 0;
}

Flex Preloader

package myComponents
{
import mx.preloaders.*;
import flash.events.ProgressEvent;

public class DownloadProgressBarSubClassMin extends DownloadProgressBar
{
   public function DownloadProgressBarSubClassMin()
   {
       super();
       // Set the download label.
       downloadingLabel="Downloading app..."
       // Set the initialization label.
       initializingLabel="Initializing app..."
       // Set the minimum display time to 2 seconds.
       MINIMUM_DISPLAY_TIME=2000;
   }

   // Override to return true so progress bar appears
   // during initialization.  
   override protected function showDisplayForInit(elapsedTime:int,
       count:int):Boolean {
           return true;
   }

   // Override to return true so progress bar appears during download.
   override protected function showDisplayForDownloading(
       elapsedTime:int, event:ProgressEvent):Boolean {
           return true;
   }
}

}

You can use your custom class in a Flex application, as the following example shows:

mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
 preloader="myComponents.DownloadProgressBarSubClassMin">
 
mx:Application>

CSS Style Example for Preloader:

ProgressBar {
borderColor: #cc0066;
barColor: #000000;
trackColors: #009999, #99ffcc;
color: #000000;
paddingLeft: 7;
paddingRight: 11;
textIndent: 14;
trackHeight: 21;
verticalGap: 20;
}