Using inputmode numeric/decimal prevents entering negative numbers on mobile devices

[ragulka]

The html inputmode attribute is useful for showing a numeric keypad on mobile devices, but it has a big downside: on some devices, it means it's not possible to enter negative numbers, because the minus sign is not shown.

Perhaps consider setting inputmode here to text when the input allows negative numbers? Or, at least allow manually setting the inputmode in the constructor options?