Better done in onStartDateChanged

This kind of C cast should be avoided I think. You should have a way to get to actual data from that index. Would be safer.

Drop the const since it's an enum for now. Or switch to const-ref if you expect that enum to grow into an object later on.

Double margins got introduced I guess.

I generally prefer to do that from C++, so that you can map the strings to the enum values directly. More type safety that way by avoiding the horrible C cast above.