Ann Dvorak's 'Sally' character.

Is it not only implied, by Frances Dee's character, that Ann Dvorak's "Sally" character is bi-racial, and "passing" for full white, or does Sally subsequently indirectly confirm that herself, when she mentions her hair being permed, but seeming to be saying that it's permed to LESS curly than it naturally is? The mentions of her hair during the restaurant scene led me to conclude that it's implied, and then that Sally semi-confirms, that she's of mixed race, partially of black heritage.