25 July 2010
Button symbols are a special type of four-frame interactive movie clip in Adobe Flash Professional. When you select the button type when creating a symbol, Flash creates a Timeline with four frames. The first three frames display the button's three possible states: Up, Over, and Down; the fourth frame defines the active area of the button. The button symbol timeline doesn't actually play linearly like a normal timeline; it reacts to mouse pointer movement and actions by jumping to the appropriate frame.
To make a button interactive, place an instance of the button symbol on the Stage and assign actions to the instance. You assign the actions to the root timeline of the Flash file. If the button is inside a movie clip, you can add the actions to the movie clip's timeline. Do not add actions to the timeline of the button symbol.
Each frame in the Timeline of a button symbol has a specific function:
To create a button symbol, follow these steps:
Editing the Hit frame is optional. The contents of the Hit frame are not visible on the Stage during playback, but the graphics you add to it define the physical area of the button that responds when clicked. This is useful when the graphic elements of the button are different sizes or unsymmetrical, which can make the button harder for a user to click.
To learn more about button symbols, see the section titled Creating buttons in the Flash documentation.