(I originally posted this on flexcomponents by mistake, sorry for cross-posting!)
I've been playing around with Flex 4 (build 6192) and it seems that the namespaces have changed a lot since previous builds. I only say this because none of the examples online seem to work. After lots of mucking around, I was able to get the following test application with these namespaces to run: <?xml version="1.0" encoding="utf-8"?> <fx:Application xmlns="http://ns.adobe.com/mxml/2009" xmlns:fx="library://ns.adobe.com/flex/spark" xmlns:mx="library://ns.adobe.com/flex/halo"> <mx:VBox> <fx:Button label="Gumbo Button"/> <mx:Button label="Halo Button" /> <fx:ButtonBar id="orangeToggleBar" requiresSelection="true"> <fx:dataProvider> <fx:ArrayCollection source="[Flash, Director, Catalyst, ColdFusion]" /> </fx:dataProvider> </fx:ButtonBar> </mx:VBox> </fx:Application> The FX namespace pointing to spark doesn't seem to be right, shouldn't it be "SP" or "S" with "FX" as a separate space? Also, what about the ns.adobe.com/flex/GUMBO library, is that gone? I saw it a lot online but I think it may have been combined into the main (unnamed) namespace. Thoughts? Baz