CBN_KILLFOCUS  1.KM_U 

The CBN_KILLFOCUS notification message is sent when a combo box loses the keyboard focus. The parent window of the combo box receives this notification message through the WM_COMMAND message.

CBN_KILLFOCUS

idComboBox = (int) LOWORD(wParam);  // identifier of combo box

hwndComboBox = (HWND) lParam;       // handle of combo box

See Also