In V21 if I had a selection and opened big file, LookIn was set to <Current Selection>
Then, deselect and open big-find again, LookIn reverts to <Current Buffer>
In V22, after deselect open big-find and LookIn remains as <Current Selection>
It should be <Current Buffer>
Actually, in V21, <Current Selection> isn't even available unless there is a selection.