WM_INPUTLANGCHANGE top-level constant Null safety
Sent to the topmost affected window after an application's input language has been changed. You should make any application-specific settings and pass the message to the DefWindowProc function, which passes the message to all first-level child windows. These child windows can pass the message to DefWindowProc to have it pass the message to their child windows, and so on.
const WM_INPUTLANGCHANGE = 0x0051;