When automatically generating a new C++ class in creator, you can specify a base class but it doesn't seem to automatically add the #include for the base class header. This was observed when the base class was another, pre-existing, class in the same project, so presumably Creator knows where the class has been defined (or can find out by searching that project's headers).

It's understandable that creator can't add the includes for every possible base class, but if it's already defined in the current project then it seems like creator could go a little farther with its code generation.