This sketch is for drag-n-drop content into and out of a page layout.

Drag an item from the list on the right to an empty layout slot on the left. You can also drag an item from one layout position to another empty one, or back to an empty slot on the right.

Issues: Currently I'm not trapping for dragging two items into the same slot, so doing so with produce unexpected results. Also, list box on the right should auto-create/destroy slots as needed, instead of having a fixed number.