Apparently works fine, the decimal separator is ',' instead of '.' when the browser is configured with Spanish locale. The problem becomes evident when you use setValue and getValue in Java code with no interaction from the user between the calls (the easiest way is making the two calls consecutively). The system will convert the decimal places into an integer number (for example, 0.5 becomes 5).

An example reproducing the bug can be found here:

http://zkfiddle.org/sample/1erkj2o/1-Bug-on-Decimalbox-when-using-Spanish-locale

I guess that the same problem happens in other locales where the decimal separator is not '.'.