Drag a sheet off the pad. Drop one scrap onto another to group them.
In the bin
Nothing in here. Drag a scrap, or a whole group by its tab, onto the bin at the bottom of the table. It waits here until you put it back or clear it out.
Boards
Each keeps its own scraps, its own bin and its own table.
The table
Scrap size
Keeping a copy
Boards live in this browser only, so save a file now and then. A file holds one board; opening one replaces the board you are on, and the undo on the chip puts it back.