Hi Jorge,
>> Or it is a matter of java or something else?
First, my pet peeve. Please use the terms "Java" and "JavaScript" correctly. NetTalk does not use, nor contain and Java. It does make use of JavaScript. Despite the names being similar they're really very different languages, and using them incorrectly confuses people who are new to NT.
What you're seeing in Chrome (and Safari) is that the fields of type "Number" automatically turn into spin boxes on those browses. That's a feature of the browser itself.
General spin boxes are on my list though, and will likely be implemented early in the new year.
cheers
Bruce