All built-in grid editors implement this interface, as do the controls in the ComponentOne C1Input library.
If you want to use a third-party editor with the C1FlexGrid, consider creating a derived class and implementing this interface.
Note that the methods in IC1EmbeddedEditor are called using reflection. Controls do not need to implement the entire interface. Any public methods with matching signatures (names, parameters, and return values) will be invoked by the grid. The grid supplies default handlers for any methods not implemented by the control.