IME Messages

The system sends IME window messages to the window procedure of the application when certain events occur that affect the IME windows. For example, the system sends the WM_IME_SETCONTEXT message to the application when a window is activated. IME-unaware application pass these messages to the DefWindowProc function which sends them to the corresponding default IME window. IME-aware applications either process these messages or forward them to their own IME windows.

You can direct an IME window to carry out a command, such as change the position of composition window, by using the WM_IME_CONTROL message. The IME notifies the application about changes to the composition string by using the WM_IME_COMPOSITION message and about general changes to the status of the IME windows by sending the WM_IME_NOTIFY message.