I have set the decimalPrecision on a NumberField to 4. This works fine as along the number of digits before the decimal is <= 13 digits. Once it exceeds 13 digits, for every new digit entered, it strips off a digit after the decimal.
This is the default behaviour of Extjs Number field? I actually need to be able to enter 15 digits before the decimal point and 4 digits after the decimal point.