OptionalFontBinaryFunction
class OptionalFontBinaryFunction<A, OA : ObservableValue<A>, B, OB : ObservableValue<B>>(argA: OA, argB: OB, lambda: (A, B) -> Font?) : BinaryFunction<Font?, A, OA, B, OB> , ObservableOptionalFont
Boilerplate which avoids having to use generics.
Similar to FontBinaryFunction, but the value can also be null.