whenExists :: String
           -> Bool -- ^ requires toWidget wrap
           -> String -> (FilePath -> Q Exp) -> Q (Maybe Exp)
whenExists = warnUnlessExists False
whenExists :: String
           -> Bool -- ^ requires toWidget wrap
           -> String -> (FilePath -> Q Exp) -> Q (Maybe Exp)
whenExists = warnUnlessExists False
whenExists = warnUnlessExists False