Clicking a non-disabled entry (red one) for unknown title still selects it! It does not call SelectTitle but still the combox shows that entry as selected. This should not happen.
So one would need to find another way to show the tooltip but not enable and selection.
I closed that issue with LSM as you cannot do that by ZOs control design.
If an entry is not enabled (control:SetMouseEnabled(false) you got no way to use handlers on that controllike OnMouseEnter etc.).
But you can do this -> with LSM v2.2
callback= (hasTitle and function() SelectTitle(vTitle.TitleID) end) or nil,
if callback is nil it still shows the tooltip but is not selectable
I guess that won't work with v2.1 though so you'd need to test it