ActionScripting Basics: Expert Mode and Normal Mode

In Expert mode, the fields that let you enter parameters are gone; there’s nothing but an open window, the code, and you—and you’re free to type anything that you want or need to. You can still click in the left-hand tree to add scripts, but customizing them is entirely up to you. This is especially useful when you need to add identifiers (such as instance names) for movie clips or other symbols, to specify that the script is supposed to act upon that specific object.

The drawback to this is that there’s nothing to stop you from making typos or other mistakes, and no hints to help you out if you get a little lost or wander into unfamiliar territory. If you try to switch back to Normal Mode with an error in your script, you won’t be able to see anything other than a message telling you that there’s a problem and you’ll have to switch back to Expert Mode to fix it.