You can scroll the ScrollView or the control with ScrollView to the top position by clicking GotoTop.

public class GotoTop : Button

Attributes

Property	Description	Default Value	Remarks
Target	ScrollView or controls with ScrollView
Animated	Whether to use animation	true
AnimationTime	Animation duration	0.2s
HidingHeight	When ScrollView scrolls this height, GotoTop will be hidden	0
AutoHiding	Whether to automatically hide	true

Case

<hc:SimplePanel Width="500" Height="400">
    <hc:ScrollViewer Name="ScrollViewerDemo" IsInertiaEnabled="True" Margin="0,10,0,0">
        <Border Height="2000" Margin="8,0">
            <Border.Background>
                <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                    <GradientStop Color="White" Offset="0"/>
                    <GradientStop Color="Black" Offset="1"/>
                </LinearGradientBrush>
            </Border.Background>
        </Border>
    </hc:ScrollViewer>
    <hc:GotoTop Animated="True" AutoHiding="True" AnimationTime="500" Target="{Binding ElementName=ScrollViewerDemo}" HorizontalAlignment="Right" VerticalAlignment="Bottom" Margin="0,0,20,20"/>
</hc:SimplePanel>