Enter a number like 1.09283409823987429873498234 into a doublebox and blur the field to be told: 'You must specify a number, rather than 1.09283409823987429873498234.'

The problem is that the doublebox does some validation in Javascript, converting the number to both BigDecimal and a double, converting back to string and checking if the results are the same. Of course double hasn't got the same number of significant digits: c=zk.fmt.Number.unformat(this._format,b,false,this._localizedSymbols),d=new zk.BigDecimal(c.raw),a=d.$toString();if(c.raw!=a&&c.raw!="-"+a){return{error:zk.fmt.Text.format(msgzul.NUMBER_REQUIRED,b)}}

I think the testing is not bad, let's just update the error message for this case.

Best,
Georg