for now we have to use:
<TextBox> <TextBox.Resources> <Style TargetType="materialDesign:SmartHint" > <Setter Property="HorizontalAlignment" Value="Center"/> </Style> </TextBox.Resources> </TextBox>
and you could add property like:
<TextBox materialDesign:PlaceHolder.HorizontalAlignment="Center" />
HintAssist.FloatingHintHorizontalAlignment effect when the text will flot.