TextInput/TextArea: option to give error state higher precedence than focus state

[joshtynjala]

Or possibly a new state that is both error and focused (which allows it have a different appearance from both states).

[MatseFR]

I like the idea of a new state for this, if the input could default to FOCUS skin if no skin is set for FOCUS+ERROR state that would prevent "breaking" anything for feathers users (even if they use a theme of their own)