<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/06/19/enabling-and-disabling-radiobutton-controls-in-a-radiobuttongroup-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white"
        creationComplete="init();">

    <mx:Script>
        <![CDATA[
            import mx.containers.ApplicationControlBar;
            import mx.containers.Form;
            import mx.containers.FormItem;
            import mx.containers.VBox;
            import mx.controls.CheckBox;
            import mx.controls.RadioButton;
            import mx.controls.RadioButtonGroup;

            private var checkBox:CheckBox;
            private var radioGroup:RadioButtonGroup;
            private var radioButton1:RadioButton;
            private var radioButton2:RadioButton;
            private var radioButton3:RadioButton;
            private var radioButton4:RadioButton;
            private var radioButton5:RadioButton;

            private function init():void {
                var appControlBar:ApplicationControlBar;
                var form:Form;
                var formItem:FormItem;

                checkBox = new CheckBox();
                checkBox.selected = true;
                checkBox.addEventListener(Event.CHANGE, checkBox_change);

                formItem = new FormItem();
                formItem.label = "enabled:";
                formItem.addChild(checkBox);

                form = new Form();
                form.styleName = "plain";
                form.addChild(formItem);

                appControlBar = new ApplicationControlBar();
                appControlBar.dock = true;
                appControlBar.addChild(form);
                Application.application.addChildAt(appControlBar, 0);

                radioGroup = new RadioButtonGroup();

                radioButton1 = new RadioButton();
                radioButton1.label = "Red";
                radioButton1.group = radioGroup;

                radioButton2 = new RadioButton();
                radioButton2.label = "Orange";
                radioButton2.group = radioGroup;

                radioButton3 = new RadioButton();
                radioButton3.label = "Yellow";
                radioButton3.group = radioGroup;

                radioButton4 = new RadioButton();
                radioButton4.label = "Green";
                radioButton4.group = radioGroup;

                radioButton5 = new RadioButton();
                radioButton5.label = "Blue";
                radioButton5.group = radioGroup;

                var vBox:VBox = new VBox();
                vBox.addChild(radioButton1);
                vBox.addChild(radioButton2);
                vBox.addChild(radioButton3);
                vBox.addChild(radioButton4);
                vBox.addChild(radioButton5);
                addChild(vBox);
            }

            private function checkBox_change(evt:Event):void {
                radioGroup.enabled = checkBox.selected;
            }
        ]]>
    </mx:Script>

</mx:Application>