Mitchell Clark, the Verge:
But then I learned that quite a few apps, including many of the built-in ones, have a quick shortcut to get at the file you’re viewing. Using this shortcut (which is officially called the proxy icon), you can easily do things like upload a PDF you have open in Preview to Google Drive without having to go looking for the file in Finder.
To be clear, this is not a new feature of the latest macOS beta or anything. I’m pretty sure I learned about it when someone mentioned it in the context of features that have been around so long that young whippersnappers like me have never even heard of them. So, yes, I am a bit late to the party here. But now that I finally learned about it, I use it all the time.
Articles like these were certainly written while proxy icons were always visible in MacOS application windows — Clark links to a 2007 TUAW piece, now at Engadget. But all instruction of how this icon works must now begin by telling users they first can hover over the title of the document to reveal a now-hidden icon, instead of a user’s curiosity being piqued by the always-visible icon.
The proxy icon should not be treated as a secret, hidden feature. It is so much more dignified and capable than that.