An issue when TextBox is binding to double and enter negative number that little than -1

Question

I have an issue when i binding a textbox to Propery and enter a negative number that is less than -1 - for example -0.45:

the textbox:

Answer 1

when you enter the decimal value it becomes 0 again so the best way to do this is using the lostfocus trigger:

Also you need to do this in the view model:

public double Txt
    {
        get { return txt; }
        set
        {
            if (!txt.Equals(value))
            {

                txt = value;
                OnPropertyChanged("Txt");
            }
        }
    }