An application sends an LB_SETLOCALE message to set the current locale of the list box. You can use the locale to determine the correct sorting order of displayed text (for list boxes with the LBS_SORT style) and of text added by the LB_ADDSTRING message.
LB_SETLOCALE wParam = (WPARAM) wLocaleID; // locale identifier lParam = 0; // not used; must be zero
The return value is the previous locale identifier. If the wLocaleID parameter specifies a locale that is not installed on the system, the return value is LB_ERR and the current list box locale is not changed.
Use the MAKELCID macro to construct a locale identifier.