Silverlight气泡图固定尺寸项目

Question

我目前正在使用silverlight工具包泡泡系列。

我创建了一个使用椭圆的控件模板。

            

            <ToolTipService.ToolTip>

                <ContentControl>
                    <StackPanel>
                        <TextBlock Text="{Binding Shortname}" />
                        <TextBlock Text="{Binding Path=Importance, stringFormat='Importance: {0}%'}"/>
                        <TextBlock Text="{Binding Path=Urgency, StringFormat='Urgency: {0}%'}"/>
                    </StackPanel>
                </ContentControl>
            </ToolTipService.ToolTip>
            <VisualStateManager.VisualStateGroups>
                <VisualStateGroup x:Name="CommonStates">
                    <VisualStateGroup.Transitions>
                        <VisualTransition GeneratedDuration="0:0:0.1"/>
                    </VisualStateGroup.Transitions>
                    <VisualState x:Name="Normal"/>
                    <VisualState x:Name="MouseOver">
                        <Storyboard>
                            <DoubleAnimation Duration="0" To="0.6" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="MouseOverHighlight"/>
                        </Storyboard>
                    </VisualState>
                </VisualStateGroup>
                <VisualStateGroup x:Name="SelectionStates">
                    <VisualStateGroup.Transitions>
                        <VisualTransition GeneratedDuration="0:0:0.1"/>
                    </VisualStateGroup.Transitions>
                    <VisualState x:Name="Unselected"/>
                    <VisualState x:Name="Selected">
                        <Storyboard>
                            <DoubleAnimation Duration="0" To="0.6" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="SelectionHighlight"/>
                        </Storyboard>
                    </VisualState>
                </VisualStateGroup>
                <VisualStateGroup x:Name="RevealStates">
                    <VisualStateGroup.Transitions>
                        <VisualTransition GeneratedDuration="0:0:0.5"/>
                    </VisualStateGroup.Transitions>
                    <VisualState x:Name="Shown">
                        <Storyboard>
                            <DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="Root"/>
                        </Storyboard>
                    </VisualState>
                    <VisualState x:Name="Hidden">
                        <Storyboard>
                            <DoubleAnimation Duration="0" To="0" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="Root"/>
                        </Storyboard>
                    </VisualState>
                </VisualStateGroup>
            </VisualStateManager.VisualStateGroups>

            <Ellipse Stroke="{TemplateBinding BorderBrush}" Fill="{TemplateBinding Background}" MouseLeftButtonDown="UIElement_OnMouseLeftButtonDown">

            </Ellipse>

        </Grid>
    </ControlTemplate>

我有一个属性Size，我将其分配给Bubble Series的SizeValuePath。

如果Size的值是10，我预计椭圆的高度和宽度也是10

不知何故泡泡系列正在缩放，是否可以为椭圆设置固定尺寸？