The following example shows how you can style the currently selected button on a Flex 4 Spark ButtonBar control by styling the various states on the Spark ButtonBarButton selector.
Full code after the jump.
The following example(s) require Flash Player 10 and the Adobe Flex 4 SDK. To download the Adobe Flash Builder 4 beta, check out the Adobe Flash Builder 4 page on the Adobe Labs site. To download the latest build of the Flex 4 SDK, see http://opensource.adobe.com/wiki/display/flexsdk/Download+Flex+4. For instructions on using the beta Flex 4 SDK in Flex Builder 3, see "Using the beta Flex 4 SDK in Flex Builder 3".
<?xml version="1.0" encoding="utf-8"?> <!-- http://blog.flexexamples.com/2009/02/15/styling-the-selected-button-on-an-fxbuttonbar-control-in-flex-gumbo/ --> <s:Application name="Spark_ButtonBar_statesStyle_test" xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" xmlns:mx="library://ns.adobe.com/flex/halo"> <fx:Style> @namespace s "library://ns.adobe.com/flex/spark"; s|ButtonBarButton:upAndSelected, s|ButtonBarButton:overAndSelected, s|ButtonBarButton:downAndSelected, s|ButtonBarButton:disabledAndSelected { baseColor: haloBlue; } </fx:Style> <s:ButtonBar id="btnBar" requireSelection="true" horizontalCenter="0" verticalCenter="0"> <s:dataProvider> <s:ArrayList source="[Red,Orange,Yellow,Green,Blue]" /> </s:dataProvider> </s:ButtonBar> </s:Application>
This entry is based on a beta version of the Flex 4 SDK and therefore is very likely to change as development of the Flex SDK continues. The API can (and will) change causing examples to possibly not compile in newer versions of the Flex 4 SDK.

{ 3 comments… read them below or add one }
These posts are alaways helpful; however, since the ‘fx’ prefix has been dropped, are ‘fx’ posts going to still be usefull?
Alan,
I think they’ll still be useful, just a bit more challenging to use since either you’ll have to know which new namespaces are needed and which prefixes aren’t, or I’ll have to undergo the massive task of updating all Fx* based examples and republish them once the API dust settles.
Neither of which are ideal solutions, but I figure me writing on some new Gumbo topics is more interesting than me writing on Flex 3 topics. Maybe?
Peter
Updated example to work with 4.0.0.8847+ API.