Steps:

1) View | Data Sources
2) Drill down to an Address book or dBase type data source. (I don't know 
whether this is a problem with other types, but I see it with both of these.)
3) Choose a table.
4) Click the Default Filter button. (BTW, this is a terrible name for this; 
it's the only filter as far as I can tell, so why "default.")
5) Specify a condition that's not based on the first field in the table.
6) Click OK. As expected, only the records matching the filter are displayed.
7) Click the Default Filter button again.

Observed: The dialog includes a condition based on the first field as well as 
the one you specified.
Expected: To see exactly the condition I specified, no more, no less.

Notes: If the original condition uses OR, what comes back not only has an 
unexpected condition, but is mangled.