Stash Shelf
This is an extension, available for purchase as needed.
You can drag local items or web images into the Stash Shelf, and then process them together: copy or move to a location, share via AirDrop, batch rename, calculate hashes, run services, etc. Supports the Quick Launch variable “$stash_items”.
Start
Display Stash Shelf in the Sidebar.

Use a custom Hotkey to bring up the floating Stash Shelf.

Use a Drag shake gesture when dragging files to bring up the floating Stash Shelf.
