Fiddle: http://jsfiddle.net/NEhG9/3/

The fiddle uses 1.2.1, however, I have reproduced it using 1.2.6

It affects IE9 and Firefox
It does not affect Chrome or Safari

I haven't tested IE8- or IE10+

The desired behavior is to allow the leading decimal to be entered, but do not update the model or set the input element's validation to valid until a valid number is entered.

Users can enter numbers with leading decimals by entering the number first, then scrolling back and entering the decimal.