When you select an item in the Library panel, a thumbnail preview of the item appears at the top of the Library panel. If the selected item is animated or is a sound file, you can use the Play button in the library preview window or the Controller to preview the item.
Use a library item in the current
document
Convert an object on the Stage
to a symbol in the library
Use a library item from the current
document in another document
Copy library items from a different
document