You may not have known that every document window in macOS has long had a proxy icon in the title bar, next to the filename. The proxy icon is not just cosmetic, they are very useful. You can drag it to Mail to attach the document to a message, to a Web browser to upload it, or to any other location you can drag a document’s icon in the Finder (top screenshot, below, showing Preview in Catalina). You can also drag proxy icons from Finder windows to Open and Save dialogs to navigate to the location of the proxy icon and even pre-fill the filename when saving. this is someting that I use on a daily basis. Alas, in macOS 11 Big Sur, in at least the Finder and Preview, Apple chose to hide the proxy icon and the drop-down menu that lets you rename, tag, or move files using controls on the title bar (middle screenshot, below). Plus, the new title bar design tends to truncate file names. The good news is you can still mouse over the filename to expand the name. It then reveals both the proxy icon and the drop-down menu (bottom screenshot, below). Apple’s desire to reduce onscreen clutter makes usage more cumbersome than before, but all the functionality is still present.