The WM_IME_SELECT message is sent to an application when the system is about to change the current IME. An application that has created an IME window should pass this message to that window so that it can retrieve the keyboard layout handle for the newly selected IME.
fSeleft = (BOOL) wParam;
hKL = (HANDLE) lParam;
No return value.
The DefWindowProc function processes this message by passing the information to the default IME window.