"Was that (she, her) on the patio?"

Question

I think her?

Answer 1

"She" is correct. "Was" is an infinitive verb with no direct object. "Her" is the objective form, "she" the nominative form.

Answer 2

I think Reed means that "was" is a linking verb, but the result is the same: Linking verbs are not followed by direct objects (objective form), but by predicate nouns or adjectives (thus the nominative "she").

http://www.chompchomp.com/terms/linkingverb.htm

http://grammar.ccc.commnet.edu/grammar/objects.htm#predicate