The BooleanToVisibilityConverter class has useless code

Mar 13 at 12:10 PM
The InternalConvert method contains that code:
else if (value is bool?)
{
    var nullable = (bool?)value;
    flag = nullable.GetValueOrDefault();
}
There is no such thing as a boxed Nullable<bool>
If you pass a Nullable<bool> to that method, the value parameter contains a boxed bool or it contains null.
If it contains a bool, the first test (value is bool) is true.
If it contains null, both tests are false.