| Building custom panels with the Extensibility API Description This sample covers how to design and build a panel to control the functions of Flash. The Trace Bitmap panel was built using the extensibility API available in Flash. The Extensibility API is a series of Javascript methods and properties that correspond to methods and properties inside the Flash application. Explore the document to see how the Javascript commands are used and to get ideas for building your own. The source file for this movie (TraceBitmap.fla) can be found in the First Run/Samples folder within the Application folder.