Quickly tell if a file has been modified by looking at the red Close window button
Mac OS X, Tips & Tricks - October 23rd, 2009 - No Comments
See the little black dot inside the red ‘close’ window button? That means the file has been modified, it’s a great way to tell if a file needs to be saved or if the file has been altered in any way while it’s active in an application. When you save the file, the black dot disappears until another change has been made.
Posted by: Bill Ellis