Override SelectedItem background in a ListBox - wpf

Question

I know this subject has been answered over and over again, but I can't achieve to implement it.
I'd like to override the way my ListboxItems are displayed when selected (and if possible, get rid of that hideous selection border).
I found on several posts over here and on the MSDN that the way to achieve it was to override the following brushes in the ItemContainerStyle:
HighlightBrushKey
ControlBrushKey
HighlightTextBrushKey
InactiveSelectionHighlightBrushKey
I tried several ways to achieve it but it systematically fails. Has an update outdated this behaviour or am I implementing it wrong?
Here is my code :
<ListBox BorderBrush="Transparent" ItemsSource="{Binding MyItemSource}" SelectedItem="{Binding SelectedItem, Mode=TwoWay}" SelectionMode="Single">
<ListBox.ItemTemplate>
<DataTemplate>
<Grid>
<Label HorizontalAlignment="Center" Margin="0 1 0 0" Foreground="Black" FontSize="14" Content="{Binding Name}"/>
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<UniformGrid Columns="{Binding ColumnCount}"/>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem">
<Style.Resources>
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="Blue"/>
<SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}" Color="Green"/>
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightTextBrushKey}" Color="Red"/>
<SolidColorBrush x:Key="{x:Static SystemColors.InactiveSelectionHighlightBrushKey}" Color="Yellow" />
</Style.Resources>
</Style>
</ListBox.ItemContainerStyle>
</ListBox>

Answer 1

Ok, so I finally achieved to override those brushs. It looks like the SystemColor brushes arent used anymore.
The way I overrode the SelectedItem's background was by defining this (most of the code comes from Blend for VS, the template to override is General Item Container).
Here is the ItemContainerStyle I used :
<Style x:Key="FocusVisual">
<Setter Property="Control.Template">
<Setter.Value>
<ControlTemplate>
<Rectangle Margin="2" SnapsToDevicePixels="true" Stroke="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}" StrokeThickness="1" StrokeDashArray="1 2"/>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<SolidColorBrush x:Key="Item.MouseOver.Background" Color="#1F26A0DA"/>
<SolidColorBrush x:Key="Item.MouseOver.Border" Color="#a826A0Da"/>
<SolidColorBrush x:Key="Item.SelectedInactive.Background" Color="#3DDADADA"/>
<SolidColorBrush x:Key="Item.SelectedInactive.Border" Color="#FFDADADA"/>
<SolidColorBrush x:Key="Item.SelectedActive.Background" Color="Gray"/>
<SolidColorBrush x:Key="Item.SelectedActive.Border" Color="Gray"/>
<Style x:Key="ListBoxItemStyle1" TargetType="{x:Type ListBoxItem}">
<Setter Property="SnapsToDevicePixels" Value="True"/>
<Setter Property="Padding" Value="0"/>
<Setter Property="HorizontalContentAlignment" Value="{Binding HorizontalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
<Setter Property="VerticalContentAlignment" Value="{Binding VerticalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="BorderBrush" Value="Transparent"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="FocusVisualStyle" Value="{StaticResource FocusVisual}"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ListBoxItem}">
<Border x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true">
<ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
</Border>
<ControlTemplate.Triggers>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsMouseOver" Value="True"/>
</MultiTrigger.Conditions>
<Setter Property="Background" TargetName="Bd" Value="{StaticResource Item.MouseOver.Background}"/>
<Setter Property="BorderBrush" TargetName="Bd" Value="{StaticResource Item.MouseOver.Border}"/>
</MultiTrigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="Selector.IsSelectionActive" Value="False"/>
<Condition Property="IsSelected" Value="True"/>
</MultiTrigger.Conditions>
<Setter Property="Background" TargetName="Bd" Value="{StaticResource Item.SelectedInactive.Background}"/>
<Setter Property="BorderBrush" TargetName="Bd" Value="{StaticResource Item.SelectedInactive.Border}"/>
</MultiTrigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="Selector.IsSelectionActive" Value="True"/>
<Condition Property="IsSelected" Value="True"/>
</MultiTrigger.Conditions>
<Setter Property="Background" TargetName="Bd" Value="{StaticResource Item.SelectedActive.Background}"/>
<Setter Property="BorderBrush" TargetName="Bd" Value="{StaticResource Item.SelectedActive.Border}"/>
</MultiTrigger>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="TextElement.Foreground" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
BTW the way to override this template using Blend :
In your Objects and Timeline panel : Right click on your ListBox > Edit Additional Templates > Edit General Item Container(ItemContainerStyle)