An application sends a CB_SETLOCALE message to set the current locale of the combo box. If the combo box has the CBS_SORT style and strings are added using CB_ADDSTRING, the locale of a combo box affects how list items are sorted.
CB_SETLOCALE wParam = (WPARAM) (WORD) wLocaleID; // locale identifier lParam = 0; // not used; must be zero
The return value is the previous locale identifier. If wParam specifies a locale not installed on the system, the return value is CB_ERR and the current combo box locale is not changed.
Use the MAKELCID macro to construct a locale identifier and the MAKELANGID macro to construct a language identifier. The language identifier is made up of a primary language identifier and a sublanguage identifier.