When you run the page, the page in the browser should look similar to this:
Drag the image and drop it over the list of beverage choices. As you drag the image over an acceptable drop area on the page, the component's background color changes. After you release the mouse button to drop the image onto the list, you should see the new item
Coffee appended to the list of existing choices:
Upon a successful drop action, the drop target rerenders by partial page rendering, thus you see the dropped value in the listbox.