IMN_OPENCANDIDATE

The IMN_OPENCANDIDATE message is sent when an IME is about to open a candidate window. An application uses this message to call ImmGetCandidateCount and ImmGetCandidateList to display candidates. The UI window creates a candidate window when it processes this message.

There is no return value.

lParam

Shows which candidate list should be updated. For example, if bit0 is 1, the first candidate list should be updated. If bit31 is 1, the 32nd candidate list should be updated.