Add CSS class when ChoiceView selection made
Add CSS class when ChoiceView selection made

So views can style the placeholder if they want to.

foam-framework/foam2,jacksonic/vjlofvhjfgm,jacksonic/vjlofvhjfgm,foam-framework/foam2,jacksonic/vjlofvhjfgm,foam-framework/foam2,foam-framework/foam2,foam-framework/foam2