I know sending ctrl-dwnarrow will open it, but I do not know how to determine if it is already opened or not. What I have done in the past to resolve this is to have the listbox have one size for closed and one size for opened:

 *--IF the size is 23, open it, else close it to 23
 IF THISFORM.List1.Height = 23 && expand it
    *OR* KEYBOARD '{ALT+DNARROW}' PLAIN CLEAR
    THISFORM.List1.Height = 170
 ELSE  && close it
    THISFORM.List1.Height = 23
 ENDIF

>How do I know if the list part of a combobox is open or closed?
>
>TIA,
>
>Alex