Folded board
Folding is a display state, not a storage state. A folded board keeps every icon assigned to it; the icons are simply not drawn. Unfolding restores the board at its previous size and position.
Fold a board with the arrow at the left of the Board widget.
Typical use is a board you want to keep organized but rarely open — an archive of installers, a project you have finished — sitting folded in a corner while the boards you use daily stay expanded.
Folding is per board and is remembered in config.json across restarts.