When the IME needs to change the RECONVERTSTRING structure (previously filled in by the application upon receiving the IMR_RECONVERTSTRING message), the application receives the IMR_CONFIRMRECONVERTSTRING message through the WM_IME_REQUEST message.
lParam = (LPARAM) lpRECONVERTSTRING;
Returns a nonzero value if the application accepts the changed RECONVERTSTRING structure. Otherwise, returns zero and the IME will use the original RECONVERTSTRING.
After the application has handled IMR_RECONVERTSTRING, the IME may or may not adjust the RECONVERTSTRING structure that is specified by the application. The IME sends WM_IME_REQUEST with IMR_CONFIRMRECONVERTSTRING to confirm the changes to the RECONVERTSTRING. If the application returns true for IMR_CONFIRMRECONVERTSTRING, the IME will generate a new composition string based on the RECONVERSTRING structure in the IMR_CONFIRMRECONVERTSTRING message. If the application returns false for IMR_CONFIRMRECONVERTSTRING, the IME will generate a new composition string based on the original RECONVERTSTRING structure that was specified by the application in the IMR_RECONVERTSTRING message.
Input Method Editor Overview, Input Method Editor Messages, IMR_RECONVERTSTRING, RECONVERTSTRING, WM_IME_REQUEST