Yes, in the listbox click event, just immediately disable (deselect) any item that you don't want clicked on by removing it from the list of items they clicked on and sending the new selection(s) back to the listbox control. For example, in GUIDE:
% Retrieve what items were selected by the user.
selectedItems = handles.lstListbox.Value;
% See if item #3 was selected.
protectedIndex = selectedItems == 3;
% If 3 was selected, disable/deselect it.
if any(protectedIndex)
% Remove from the selection array variable.
selectedItems(protectedIndex) = []
% Update listbox with new selection.
handles.lstListbox.Value = selectedItems;
end
