An application sends the IMC_GETOPENSTATUS message to an IME window to determine whether the IME is open.
msg = (UINT) WM_IME_CONTROL;
wParam = (WPARAM) IMC_GETOPENSTATUS;
lParam = 0;
Returns nonzero if the current IME is open, zero otherwise.
Windows NT: Requires version 4.0 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Input Method Editor Overview, Input Method Editor Messages