Squiggly SDK can be used to add spell check for Flex components.

1. Download Squiggly SDK from Adobe Labs.

2. Create a new Flex Project.

3. Copy the libs in the SDK to the libs in the Project folder.

4. Copy the contents in the src folder of the SDK to the src folder in your Project.

5. Import the Class

import com.adobe.linguistics.spelling.SpellUI;

6. Create a text area component

<s:TextArea id="txt" initialize="txt_initializeHandler(event)"/>

7. In the initialize handler add spell check

private function txt_initializeHandler(event:FlexEvent):void {
    SpellUI.enableSpelling(txt, "en_US");  // spell check for en_US