Textfield widget with Mask Number

I provided text field widget with Mask Number. This field is displaying '-' symbol as default. Whenever I typed first digit the symbol '-' replaced with digit. But if the digit value passing from binding, then this widget is displaying '-9' Even though if the passed value is positive it is showing the digit after the symbol -. 

As i dont have option to use disable property in numeric entry widget, i have to go ahead with textfield with mask. 

Kindly tell me how to overcome this symbol - when numeric value is passed from parameters.