This animation demonstrates the following actions:

• Importing an image directly to the Thumbnail pane via drag & drop from the desktop.
• Deleting a slide.
• Duplicating a slide by dragging it with the Alt/Opt key.

Making drop-targets of the gaps between slides allows for quicker placement of slides at a precise location. It simplifies the workflow to a single click-and-drag gesture without requiring an initial selection to determine slide placement.