<!-- シンプルな連結マーカー -->
<c1:ChartPanelObject x:Name="obj" Attach="DataX"
                     Action="MouseMove"
                     DataPoint="-1,-1"
                     HorizontalAlignment="Center"
                     VerticalAlignment="Top"
                     Width="60" Height="50">
    <c1:ChartPanelObject.RenderTransform>
        <TranslateTransform Y="-50"/>
    </c1:ChartPanelObject.RenderTransform>
    <Grid DataContext="{Binding RelativeSource={x:Static RelativeSource.Self},Path=Parent}" Opacity="0.8">
        <Path Data="M0.5,0.5 L23,0.5 23,23 11.61165,29.286408 0.5,23 z" Stretch="Fill" Fill="#FFF1F1F1" Stroke="DarkGray" StrokeThickness="1"/>
        <StackPanel VerticalAlignment="Center" HorizontalAlignment="Center">
            <TextBlock Text="Value" Margin="2 0"/>
            <TextBlock x:Name="label" Text="{Binding DataPoint.Y, StringFormat=c2}" FontWeight="Bold" Margin="2"/>
        </StackPanel>
    </Grid>
</c1:ChartPanelObject>