text input: Reset hints when text input gone
This ensures that when the keyboard is force brought up next time, the user is not stuck with an overlay they can't switch.
As a downside, there's a blink of default hint before the keyboard hides.
This fixes #256 (closed)
Not sure what a "proper" solution for this should be, but trading a functional bug for a cosmetic one that people may rarely notice counts as a win for me.
I submitted another approach here !421 (merged)