Type Alias CellFn 

pub type CellFn<Msg = Callback> = Box<dyn Fn() -> Box<dyn Widget<Msg>>>;

A slot built on demand: the closure a Table header, a Table row or a Kanban column takes for a cell that holds a widget rather than a string. It is called again on every rebuild, so it hands back a fresh widget each time.

Aliased Type

pub struct CellFn<Msg = Callback>(/* private fields */);