What is the standard convention of calling static member functions for the Microsoft compiler? Can I change it by putting WINAPI in front of it?
The default call standard is cdecl. Yes, you can override this and specify a calling convention. There is nothing special about static member functions in this regard.
The default standard is what is ever set in the project settings (C / C ++ → Advanced → Calling Convention), the default is __cdecl (command line option /Gd )
__cdecl
/Gd