function focusPickerOnceOpened() {

        if (IS_DEFAULT_THEME && supportsTransitions) {
            P.$holder.find('.' + CLASSES.frame).one('transitionend', function() {
                P.$holder.eq(0).focus()
            })
        }
        else {
            setTimeout(function() {
                P.$holder.eq(0).focus()
            }, 0)
        }
    }
Prepare the hidden input element along with all bindings.