Dragging the buttons will add URLs to the text editor

If the buttons are accidentally dragged to the editor, they will drop the link URL into the text, which can be confusing:


Reproduce the accidental drag from a button into the text editor in the browser, then trace the button and editor drag-and-drop handling. The issue provides no file or test entry point, so first locate where button links and editor drops are handled. Done means dragging a button into the editor no longer inserts its URL.

Written by the indexing model from the issue text.