Currently all available options are attributes that can be hard-coded in the input component (well, except
setting, which is passed to the prop call which is bound to
Providing a default value would likely require some sort of callback-based API because there is no standardized way to tell when that value should be returned. Is it when no value exists for that setting (undefined)? when the setting is null? when the setting is an empty string?
If we do add this option we will have to make clear that this is purely visual, setting a default value there would not ensure that value is ever used, because the user is not required to edit and save the settings before using the extension, so any default value should likely be set in the backend.
It's expected that more advanced setting inputs use the callback syntax and return their own input as Mithril template. This allows defining a custom getter/setter for the setting value and more.