When writing code that contains a not yet included class you can perform a quick fix on this class to add the respective include.

The includes seem to get inserted based on some alphabetical order logic - but this might break some basic rule of thumb.

Assume class A - defined inside a.h and a.cpp

Now write class B (b.h and b.cpp) and use class A without including it. Now perform the quick fix on the used class A to include a.h. The new include will be inserted before the include of b.h.