<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <Style x:Key="CheckBox_VizConnection" TargetType="CheckBox">
        <Setter Property="FocusVisualStyle" Value="{x:Null}"></Setter>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="CheckBox">
                    <Grid>
                        <Ellipse x:Name="e1" Width="16" Height="16" Fill="Red" Visibility="Visible"></Ellipse>
                        <Ellipse x:Name="e2" Width="16" Height="16" Fill="Green" Visibility="Collapsed"></Ellipse>
                    </Grid>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsChecked" Value="True">
                            <Setter TargetName="e1" Property="Visibility" Value="Collapsed"></Setter>
                            <Setter TargetName="e2" Property="Visibility" Value="Visible"></Setter>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>


</ResourceDictionary>