I saw those demos but unfortunately my use case is slightly more granular.
- Page overall culture set to en-US.
- First text box uses Yen for currency - update currency symbol, decimals, positive/negative formats, but everything else is en-US.
- Second text box uses US dollars for currency - no updates.
- Third text box uses Euros for currency - update currency symbol, decimals, positive/negative formats, but everything else is en-US.
It'd be preferable to not load three different cultures on the page just for that. Plus they're all technically "en-US" so there'd be some interesting customization where we have, like, "en-US-Yen" and "en-US-Euro" - combinatoric sets of cultures on a culture/currency basis. Or a programmatic handler to generate all of those.
Most likely we'll go with a simpler option: override the NumericTextBox _format method so I can get the current culture for the box... and then look at some additional data-* attributes on the box to spot-weld the overrides into place.
It would be nice to have an event for the NumericTextBox format so I can do this in a more supported way.