Saving documents when you undo steps

By default, when you undo a step using Edit > Undo or the History panel, the file size of the Flash document does not change, even if you delete an item in the document. For example, if you import a video file into a document, and then undo the import, the file size of the document still includes the size of the video file. This is because any items that you delete from a document when performing an Undo command are preserved in case you want to restore the items with a Redo command. You can permanently remove the deleted items from the document, and reduce the document file size, by using the Save and Compact command.

To permanently remove items deleted by the Undo command: