Sorry again,
I do have a style defined for the legend for my TOC control. The "IsChecked" property is bound to "IsVisible" but it does not seem to work. When I step to the code, I see that the layers are not visible but once the TOC display, the layers are all selected.
<Grid VerticalAlignment="Center">
<CheckBox IsChecked="{Binding IsEnabled, Mode=TwoWay}" />
<CheckBox IsChecked="{Binding IsEnabled}" IsEnabled="{Binding IsVisible}" IsHitTestVisible="False" />
</Grid>
<Style TargetType="esri:Legend">
<Setter Property="LayerItemsMode" Value="Tree" />
<Setter Property="ShowOnlyVisibleLayers" Value="False" />
<Setter Property="MapLayerTemplate" >
<Setter.Value>
<DataTemplate>
<StackPanel>
<StackPanel.Resources>
<DataTemplate x:Key="BusyIndicatorTemplate">
<Grid x:Name="BusyIndicator" Background="Transparent" Margin="3,0"
HorizontalAlignment="Left" VerticalAlignment="Center" RenderTransformOrigin="0.5,0.5" >
<Grid.Triggers>
<EventTrigger RoutedEvent="Grid.Loaded">
<EventTrigger.Actions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation Duration="0:0:1" RepeatBehavior="Forever" To="360" Storyboard.TargetName="BusyIndicator"
Storyboard.TargetProperty="(UIElement.RenderTransform).(RotateTransform.Angle)" />
</Storyboard>
</BeginStoryboard>
</EventTrigger.Actions>
</EventTrigger>
</Grid.Triggers>
<Grid.RenderTransform>
<RotateTransform />
</Grid.RenderTransform>
<Ellipse Fill="#1E525252" Margin="11,2,11,20" Width="2" Height="2"/>
<Ellipse Fill="#3F525252" Height="3" Width="3" VerticalAlignment="Top" HorizontalAlignment="Right" Margin="0,4,5,0" />
<Ellipse Fill="#7F525252" Width="4" HorizontalAlignment="Right" Height="4" VerticalAlignment="Top" Margin="0,9,1,0" />
<Ellipse Fill="#BF525252" Height="5" Width="5" VerticalAlignment="Bottom" Margin="0,0,3,3" HorizontalAlignment="Right" />
<Ellipse Fill="#FF525252" Height="6" Width="6" VerticalAlignment="Bottom" Margin="9,0" />
</Grid>
</DataTemplate>
</StackPanel.Resources>
<ToolTipService.ToolTip>
<StackPanel MaxWidth="450">
<TextBlock FontWeight="Bold" Text="{Binding Layer.CopyrightText}" TextWrapping="Wrap" />
<TextBlock Text="{Binding Description}" TextWrapping="Wrap" />
<TextBlock Text="{Binding Layer.Url, StringFormat='Url : {0}'}" />
<TextBlock Text="{Binding MinimumResolution, StringFormat='Minimum Resolution : {0:F6}'}" />
<TextBlock Text="{Binding MaximumResolution, StringFormat='Maximum Resolution : {0:F6}'}" />
</StackPanel>
</ToolTipService.ToolTip>
<StackPanel Orientation="Horizontal">
<Grid VerticalAlignment="Center">
<CheckBox IsChecked="{Binding IsEnabled, Mode=TwoWay}" />
<CheckBox IsChecked="{Binding IsEnabled}" IsEnabled="{Binding IsVisible}" IsHitTestVisible="False" />
</Grid>
<ContentControl ContentTemplate="{StaticResource BusyIndicatorTemplate}"
Visibility="{Binding BusyIndicatorVisibility}" VerticalAlignment="Center"/>
<Slider Minimum="0" Maximum="1" Value="{Binding Layer.Opacity, Mode=TwoWay}" Width="30" VerticalAlignment="Center" />
<TextBlock Text="{Binding Label}" FontWeight="Bold" VerticalAlignment="Center" />
</StackPanel>
</StackPanel>
</DataTemplate>
</Setter.Value>
</Setter>