Set tooltip background
<?xml version="1.0"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" creationComplete="setToolTipStyle()"> <mx:Script> import mx.styles.StyleManager; private function setToolTipStyle():void { StyleManager.getStyleDeclaration("ToolTip").setStyle("backgroundColor","#33CC99"); } </mx:Script> <mx:Button id="b1" label="Click Me" toolTip="This Button does nothing."/> </mx:Application>