<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/10/03/toggling-form-item-visibility-in-a-form-container-in-flex/ -->
<mx:Application name="FormItem_includeInLayout_test"
        xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white" viewSourceURL="srcview/index.html">

    <mx:Style>
        Form {
            indicatorGap: 0;
            paddingLeft: 0;
            paddingRight: 0;
            paddingTop: 0;
            paddingBottom: 0;
        }
    </mx:Style>

    <mx:ApplicationControlBar dock="true">
        <mx:Button id="bccButton"
                label="Show BCC"
                toggle="true"
                selected="false" />
        <mx:Button id="fromButton"
                label="Show From"
                toggle="true"
                selected="false" />
    </mx:ApplicationControlBar>

    <mx:HBox width="100%">
        <mx:Button id="sendButton"
                label="Send"
                height="100%" />
        <mx:Form width="100%">
            <mx:FormItem label="From:"
                    includeInLayout="{fromButton.selected}"
                    visible="{fromButton.selected}"
                    width="100%">
                <mx:ComboBox id="fromComboBox"
                        width="100%" />
            </mx:FormItem>
            <mx:FormItem label="To:" width="100%">
                <mx:TextInput id="toTextInput"
                        width="100%" />
            </mx:FormItem>
            <mx:FormItem label="CC:" width="100%">
                <mx:TextInput id="ccTextInput"
                        width="100%" />
            </mx:FormItem>
            <mx:FormItem label="BCC:"
                    includeInLayout="{bccButton.selected}"
                    visible="{bccButton.selected}"
                    width="100%">
                <mx:TextInput id="bccTextInput"
                        width="100%" />
            </mx:FormItem>
            <mx:FormItem label="Subject:"
                    width="100%">
                <mx:TextInput id="subjectTextInput"
                        width="100%" />
            </mx:FormItem>
        </mx:Form>
    </mx:HBox>

    <mx:TextArea id="bodyTextArea"
            width="100%"
            height="100%" />

</mx:Application>