Power Souce: EditTexts don't allow negative values for PV1 and PV2

[marcnause]

Actual Behaviour

The values for PV1 and PV2 may be negative, but the EditTexts for PV1 and PV2 don't allow to enter negative values.

Expected Behaviour

The EditTexts should allow negative values for PV1 and PV2.

It is possible to allow negative decimal numbers as values by setting the android:inputType to numberSigned|numberDecimal, but this introduces problems due to a bug in the keyboards of older Android version (before Android O). A workaround is required. See https://stackoverflow.com/questions/3821539/decimal-separator-comma-with-numberdecimal-inputtype-in-edittext/51983392 for more information and hints.

Steps to reproduce it

1. Open app
2. Open Power Souce
3. Try to enter negative value for PV1 or PV2 with keyboard

Would you like to work on the issue? Maybe