When dragging multiple files in Google Drive, it does the slick animation where it compresses the files into a stack and displays a counter for the files in the top right corner. The answer I am looking for isn't about the exact CSS required for the animation, but I am looking for an answer that can describe the overall process of how this is done, beginning with the dragstart DOM event. From what I know, when an element starts to get dragged, the browser takes a bitmap screenshot of the element and uses that as the drag cursor image. I also know that you can set the drag image on the dragstart event, however, how are they dynamically generating and setting the drag image with the file name in it?