An application sends a ZGM_COMBOCLEAR message to initialize the incell droplist combo box.
ZGM_COMBOCLEAR wParam = (WPARAM) (BOOL) fSort; //sort option flag lParam = 0; //not used; must be zero
This message does not return a value.
The ZGM_COMBOCLEAR message is sent in response to a ZGN_LOADCOMBO notification message. The ZGN_LOADCOMBO notification message is sent to the application when a cell with an edit value of 2 is being edited by the user.