List page anchors while adding a new anchor link on the same page

While adding an anchor link on a page, it would be useful list the anchors of the same page directly in the Edit link window.
Without this feature the user has to remember all the names of the anchors of the page to write the "#anchorname" link.

Maybe a listbox when you write the # sign? Or just show the list of all the anchors just below the text input field...