Decimal separator key not visible when DigitsKeyListener is set

I want to allow the user to enter numbers with a decimal separator (comma or dot) depending on the region.

Now I'm using DigitsKeyListener to enable comma as separator for some locales (e.g. Poland, Germany).

val separator = DecimalFormatSymbols.getInstance().decimalSeparator
editTextValue.keyListener = DigitsKeyListener.getInstance("-0123456789$separator")

This code is written in kotlin.

If software keyboard is Gboard or other third party keyboard, then everything is fine and user can use comma or dot as separator.

But when user use stock keyboard and DigitsKeyListener is set, then not all keys are visible and user is not able to add separator.

This is my EditText code:

<android.support.design.widget.TextInputLayout
    android:id="@+id/textInput"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginStart="8dp"
    app:hintTextAppearance="@style/Lorin.Theme.TextInputLayout"
    app:layout_constraintLeft_toRightOf="@id/imageInfo"
    app:layout_constraintRight_toLeftOf="@id/buttonHistoryNumeric">

    <android.support.design.widget.TextInputEditText
        android:id="@+id/editTextValue"
        style="@style/Lorin.EditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:imeOptions="flagNavigateNext"
        android:inputType="number|numberSigned|numberDecimal"
        android:maxLines="1"
        tools:hint="Range"/>
</android.support.design.widget.TextInputLayout>

---

val separator = DecimalFormatSymbols.getInstance().decimalSeparator
//editTextValue.keyListener = DigitsKeyListener.getInstance("-0123456789$separator")

When line with DigitsKeyListener is commented, key for separator is visible but only available separator is dot

Do you have any ideas how to use comma as separator on stock keyboard?

from Decimal separator key not visible when DigitsKeyListener is set