The ItemRenderer in the Flex 4 Spark components provides the useful ability to automatically draw the backgrounds of the item renderers, however it is limited to only drawing them with an alpha of 1 or 0. By extending the ItemRenderer class and overriding the mx_internal drawBackground() method, we are able to set the fill alpha [...]
Ivan Tenger over at flashcommander has posted a very useful AutoComplete component using the Spark component architecture. Click here to have a look.