When creating a DropdownButton, one can specify a disabled hint widget when none of the available options are selected. However, when DropdownButton is disabled and a disabled hint/hint is specified, it is wrapped by a DropdownMenuItem by default, whereas a DropdownButton that is enabled is not wrapped by DropdownMenuItem:

Sample code available here.

We should make this consistent so that there isn't a mismatch in behavior between enabled and disabled states.