Edited Issue: NumericUpDown.FormatString improvement [19205]

The NumericUpDown.FormatString property should support format mask in the same way the BindingBase.StringFormat property does. So I could write something like FormatString="{}{0:N0} ms" in XAML to get a "1,000 ms" display.

For compatibility reasons maybe a second property is required (or some clever parsing for "{0"...).