别找了,Flex自己是没这个功能的。下面这些链接都讲解了怎么自行实现。

转自:http://bbs.airia.cn/FLEX/thread-4095-1-1.aspx

Background image repeat in flex 3 - DEGRAFA!

e.g:

Application {
   background-image:    Embed("assets/images/the_image_goes_here.png");
   background-repeat:   repeat;
   background-position: center;
   background-blend:    multiply;
   borderSkin:          ClassReference("com.degrafa.skins.CSSSkin");
} 

此外还有: