I could think of 2 solutions:
1. Fix the state selector to accept int and string as a state.
2. Fix the MSCheckbox call to provide only ints for the state.

2. could be considered as leaving a breaking change in. However the MSCheckbox class is documented nowhere, so as long as we correct all internal uses, it's okay to do so.

I'd rather keep variable's type consistent here, so I'll go with 2.