AUTO scale does not work if the value of decimalebox is bind form VM.
Test case:
http://zkfiddle.org/sample/fscpkj/7-Auto-scale-of-decimalbox-not-work#source-1

1.For the Decimalbox 1, enter 1.23, AUTO scale works and shows 1.23 in the decimalbox.
2.For the Decimalbox 2, which value is bind from VM as 12.3, AUTO scale does not work and shows "1.2300......".
3.Enter a value, say 1.23, into Decimalbox 2, AUTO scale does not work neither.