Reverse direction; if true, focuses the previous node.
Tree action that switches focus to the previous, or next node. If no node is currently focused, returns a tree action to focus the first or the last node, equivalent to focusFirst or focusLast.
You can use .then on the returned action to run a callback the moment the focus switches.
focusNext focuses the next, and focusPrevious focuses the previous node, relative to the one that is currently focused.