I am frequently asked why the title bar of certain OS X applications have icons beside the titles and others do not. That little icon is called a proxy icon and it has some fun, helpful features associated with it.
What exactly is the proxy icon? Let me show you…
The proxy icon will appear in many different applications including Preview, Textedit, Pages, Numbers, Word, etc. It is typically in applications that deal with objects such as images or documents.
Once an application saves the document, the proxy icon will appear in the title.
If you want to create an alias, you can drag the proxy icon to the desktop.
If you want to copy the file, you can hold the option key down and drag the proxy icon to the desktop.
If you want to see the path of the current document, you can hold the command key down and click the proxy icon.
You can also drag the icon into another application which will either open that document in that application or paste the complete path into the document. For example, you can drag the proxy icon from an image file in Preview into Photoshop or any other image editor.
The proxy icon features may not work if the current version of the document (or image) has not been saved. Some applications may not support the proxy icon features or use the proxy icon function at all.
The following screencast show the proxy icon features in additional detail:
