[TextBoxHelper] ClearTextButton and FloatingWatermark collide when used on NumericUpDown

[DMtsdt]

Describe the bug

When applied to a NumericUpDown with ButtonsAlignment="Left", and TextBoxHelper.ClearTextButton and TextBoxHelper.UseFloatingWatermark applied - FloatingWatermark appearks on top of ClearTextButton instead of the NumericUpDown's Value.

Steps to reproduce

On a NumericUpDown:

1. Apply TextBoxHelper.Watermark with any text.
2. Set TextBoxHelper.UseFloatingWatermark and TextBoxHelper.ClearTextButton to True.
3. Set ButtonsAlignment to Left.
4. Type anything in the NumericUpDown.

<mm:NumericUpDown  mm:TextBoxHelper.Watermark="Lorem Ipsum"
                   mm:TextBoxHelper.ClearTextButton="True"
                   mm:TextBoxHelper.UseFloatingWatermark="True"
                   ButtonsAlignment="Left"/>

Expected behavior

FloatingWatermark should appear on top of the NumericUpDown text element.

Actual behavior

FloatingWatermark appears on top of the TextBoxHelper.ClearTextButton instead.

Environment

MahApps.Metro version: v2.4.3
Windows build number: Win10 1903 [Version 10.0.18362.836]
Visual Studio: 2019 16.8.2
Target Framework: .Net v4.6.2

Screenshots

No value:

With value: