Look can be compared to the architectural style of the building as a whole. Layer two is product organization. When similar features are organized consistently across products, the user can easily find commands, editors, and controls, and predict where to locate a specific feature. Layer three consists of common functional components such as property windows, command dialogs, text rulers, and inspectors that can work the same way even in very different applications. Common functional components can be thought of as standard designs for areas that are common to every building.
Interaction techniques are similar to a work flow for common activities.
For example, a user can bypass the menu by double clicking an object to open an editor window. Acceleration methods are like standard shortcuts through the building to frequently used areas. MUI is based on sound graphical user interface principles, adapted for the special requirements of digital arts, multimedia, and video applications by Macromedia. As the standard for all Macromedia applications, MUI will grow as new application features are developed, and as new applications become part of Macromedia Studios. Until then, keep those questions coming.