CBN_SETFOCUS  B9XBMS 

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

CBN_SETFOCUS

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

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

See Also