That's exactly what I found happens with that control. I also gave up on it.

>After beating my head against the wall for many hours, I give up on maskedinput.js. It works and then it does not work. And even when it works, it does not work well. For example, I wanted to use it in one textbox where user would be entering time; in hours and decimal. For example, 2.5 (for 2 and half hours). I set up the input mask to 999.99. What happens is that (when it works) if you enter any value of less than 5 digits (e.g. 2.5) the value disappears on leaving the textbox. The only way to make the number stay in the textbox is to enter all 5 digits (e.g. 888.33). I will have to relay on the user to enter the number in the correct format.
>Just want to let those who helped me in this thread know.