Hi Raj, Thanks for testing. I've not doubled checked but I think you need both ApacheFlexSpellingUI.swc and ApacheFlexSpellingUIEx.swc for it to work with spark components. While the swc's have different names the common classes (SpellUI + SpellingContextMenu) have the same package name (com.adobe.linguistics.spelling), basically ApacheFlexSpellingUIEx.swc uses the ui classes from ApacheFlexSpellingUI.swc.
Thanks, Justin