You can scan Listbox for Listbox.ListItem starting with "\".
Something like:
with ThisForm.List1
FOR i= 1 to .ListCount
if .ListItem(i) = "\"
*disabled
endif
endfor
endwith

>Hi everybody,
>
>An item in a ListBox or ComboBox control can be disabled by placing a backslash (\) before the item. How do I determine whether an item is disabled or not?
>
>Thank you,
>Ali