You may be right, but what we need is the multi-column control, which I think is ctMdays. That one is not free. I got the impression if you needed multiple columns, you could not use ctDays for that.

Sorry - you are correct. But even if it is not free, you gotta ask yourself if creating one yourself from scratch is going to cost your client more than if you just bought a (set of) great controls that already do what you want.