主要是滑鼠移入顯示滾動條，移出滑鼠滾動條消失，按住拖拽改變滾動條外觀顏色等；

 關鍵點幾個點是：

1：在ScrollViewer 的自定義模板中 定義好如下幾個事件觸發器：

 <EventTrigger RoutedEvent="ScrollChanged">

用於滾動條滾動時的觸發顯示；

<EventTrigger RoutedEvent="MouseEnter"

用於響應滑鼠移入時顯示滾動條 

 <EventTrigger RoutedEvent="MouseLeave"

用於響應滑鼠移出時滾動條消失

2：當按住滾動滑塊時，滑塊的外觀顏色變化：

    ScrollViewer的滑塊就是Thumb，在自定義Thumb的模板中響應IsDragging屬性，改變模板中自定義的元素外觀屬性就可以達到效果。

網上找了很多自定義樣式都沒有談到按下後滾動滑塊顏色改變的效果，折騰了一會才找到通過IsDragging可以實現。

一個完整的ScrollViewer樣式貼下面，記錄於此，供日後查閱方便：

<Style x:Key="ScrollBarThumb" TargetType="{x:Type Thumb}">
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="BorderBrush" Value="White"/>
        <Setter Property="IsTabStop" Value="false"/>
        <Setter Property="Opacity" Value="1"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type Thumb}">
                    <Rectangle x:Name="recThumb"  Fill="{TemplateBinding BorderBrush}" RadiusX="3"  RadiusY="3" />
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsDragging" Value="True">
                            <Setter Property="Fill" TargetName="recThumb" Value="#606060"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
                
            </Setter.Value>
        </Setter>
    </Style>
	

 <Style x:Key="HorizontalScrollBarPageButton" TargetType="{x:Type RepeatButton}">
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="Focusable" Value="false"/>
        <Setter Property="IsTabStop" Value="false"/>
        <Setter Property="Opacity" Value="0"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type RepeatButton}">
                    <Rectangle Fill="{TemplateBinding Background}" Width="{TemplateBinding Width}" Height="{TemplateBinding Height}"/>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
    <Style x:Key="VerticalScrollBarPageButton" TargetType="{x:Type RepeatButton}">
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="Focusable" Value="false"/>
        <Setter Property="IsTabStop" Value="false"/>
        <Setter Property="Opacity" Value="0"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type RepeatButton}">
                    <Rectangle Fill="{TemplateBinding Background}" Width="{TemplateBinding Width}" Height="{TemplateBinding Height}"/>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
 

<Style x:Key="for_scrollbar"
           TargetType="{x:Type ScrollBar}">
        <Setter Property="Stylus.IsPressAndHoldEnabled" Value="false"/>
        <Setter Property="Stylus.IsFlicksEnabled" Value="false"/>
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="Margin" Value="0,1,0,6"/>
        <Setter Property="Width" Value="10"/>
        <Setter Property="MinWidth" Value="10"/>
        <Setter Property="Opacity" Value="0"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ScrollBar}">
                    <Grid x:Name="Bg" SnapsToDevicePixels="true">
                        <Track x:Name="PART_Track"   IsEnabled="{TemplateBinding IsMouseOver}" IsDirectionReversed="true">
                            <Track.DecreaseRepeatButton>
                                <RepeatButton Style="{StaticResource VerticalScrollBarPageButton}" Command="{x:Static ScrollBar.PageUpCommand}"/>
                            </Track.DecreaseRepeatButton>
                            <Track.IncreaseRepeatButton>
                                <RepeatButton Style="{StaticResource VerticalScrollBarPageButton}" Command="{x:Static ScrollBar.PageDownCommand}"/>
                            </Track.IncreaseRepeatButton>
                            <Track.Thumb>
                                <Thumb Style="{StaticResource ScrollBarThumb}"/>
                            </Track.Thumb>
                        </Track>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Style.Triggers>
            <Trigger Property="Orientation" Value="Horizontal">
                <Setter Property="Background" Value="Transparent"/>
                <Setter Property="Margin" Value="1,0,6,0"/>
                <Setter Property="Height" Value="10"/>
                <Setter Property="MinHeight" Value="10"/>
                <Setter Property="Width" Value="Auto"/>
                <Setter Property="Opacity" Value="0"/>
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate TargetType="{x:Type ScrollBar}">
                            <Grid x:Name="Bg" SnapsToDevicePixels="true">
                                <Track x:Name="PART_Track" IsEnabled="{TemplateBinding IsMouseOver}">
                                    <Track.DecreaseRepeatButton>
                                        <RepeatButton Style="{StaticResource HorizontalScrollBarPageButton}" Command="{x:Static ScrollBar.PageLeftCommand}"/>
                                    </Track.DecreaseRepeatButton>
                                    <Track.IncreaseRepeatButton>
                                        <RepeatButton Style="{StaticResource HorizontalScrollBarPageButton}"  Command="{x:Static ScrollBar.PageRightCommand}"/>
                                    </Track.IncreaseRepeatButton>
                                    <Track.Thumb>
                                        <Thumb Style="{StaticResource ScrollBarThumb}"/>
                                    </Track.Thumb>
                                </Track>
                            </Grid>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Trigger>
        </Style.Triggers>
    </Style>

 <!-- ScrollViewer -->
    <Style TargetType="{x:Type ScrollViewer}">
        <Setter Property="BorderBrush" Value="LightGray"/>
        <Setter Property="BorderThickness"  Value="0"/>
        <Setter Property="HorizontalContentAlignment" Value="Left"/>
        <Setter Property="HorizontalScrollBarVisibility"  Value="Auto"/>
        <Setter Property="VerticalContentAlignment" Value="Top"/>
        <Setter Property="VerticalScrollBarVisibility" Value="Auto"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ScrollViewer}">
                    <Border BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}"
                            SnapsToDevicePixels="True">
                        <Grid Background="{TemplateBinding Background}">
                            <ScrollContentPresenter
                                Cursor="{TemplateBinding Cursor}"
                                Margin="{TemplateBinding Padding}"
                                ContentTemplate="{TemplateBinding ContentTemplate}"/>
                            <ScrollBar x:Name="PART_VerticalScrollBar"
                                       Opacity="1"
                                       HorizontalAlignment="Right"
                                       Maximum="{TemplateBinding ScrollableHeight}"
                                       Orientation="Vertical"
                                       Style="{StaticResource for_scrollbar}"
                                       ViewportSize="{TemplateBinding ViewportHeight}"
                                       Value="{TemplateBinding VerticalOffset}"
                                       Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}"
                                       Width="10"/>
                            <ScrollBar x:Name="PART_HorizontalScrollBar"
                                       Opacity="1"
                                       Maximum="{TemplateBinding ScrollableWidth}"
                                       Orientation="Horizontal"
                                       Style="{StaticResource for_scrollbar}"
                                       VerticalAlignment="Bottom"
                                       Value="{TemplateBinding HorizontalOffset}"
                                       ViewportSize="{TemplateBinding ViewportWidth}"
                                       Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}"
                                       Height="10"/>
                        </Grid>
                    </Border>
                    <ControlTemplate.Triggers>
                        <EventTrigger RoutedEvent="ScrollChanged">
                            <BeginStoryboard>
                                <Storyboard>
                                    <DoubleAnimation  
                                        Storyboard.TargetName="PART_VerticalScrollBar"  
                                        Storyboard.TargetProperty="Opacity"  
                                        To="1"  
                                        Duration="0:0:1"/>
                                    <DoubleAnimation  
                                        Storyboard.TargetName="PART_VerticalScrollBar"  
                                        Storyboard.TargetProperty="Opacity"  
                                        To="0"  
                                        Duration="0:0:1"  
                                        BeginTime="0:0:1"/>
                                    <!--<DoubleAnimation  
                                        Storyboard.TargetName="PART_HorizontalScrollBar"  
                                        Storyboard.TargetProperty="Opacity"  
                                        To="1"  
                                        Duration="0:0:1"/>
                                    <DoubleAnimation  
                                        Storyboard.TargetName="PART_HorizontalScrollBar"  
                                        Storyboard.TargetProperty="Opacity"  
                                        To="0"  
                                        Duration="0:0:1"  
                                        BeginTime="0:0:1"/>-->
                                </Storyboard>
                            </BeginStoryboard>
                        </EventTrigger>
                        <EventTrigger RoutedEvent="MouseEnter"  
                                      SourceName="PART_VerticalScrollBar">
                            <BeginStoryboard>
                                <Storyboard>
                                    <DoubleAnimation  
                                        Storyboard.TargetName="PART_VerticalScrollBar"  
                                        Storyboard.TargetProperty="Opacity"  
                                        To="1"  
                                        Duration="0:0:1"/>
                                </Storyboard>
                            </BeginStoryboard>
                        </EventTrigger>
                        <EventTrigger RoutedEvent="MouseLeave"  
                                      SourceName="PART_VerticalScrollBar">
                            <BeginStoryboard>
                                <Storyboard>
                                    <DoubleAnimation  
                                        Storyboard.TargetName="PART_VerticalScrollBar"  
                                        Storyboard.TargetProperty="Opacity"  
                                        To="0"  
                                        Duration="0:0:1"/>
                                </Storyboard>
                            </BeginStoryboard>
                        </EventTrigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>