Having a style like this:

<Style x:Key="{x:Type TreeViewItem}" TargetType="{x:Type TreeViewItem}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type TreeViewItem}">
                <Border x:Name="Border" Padding="2" SnapsToDevicePixels="true" BorderBrush="{StaticResource Brush_ItemBorder}" BorderThickness="{TemplateBinding BorderThickness}">
                    <ContentPresenter  Content="{TemplateBinding Header}" ContentTemplate="{TemplateBinding HeaderTemplate}" ContentTemplateSelector="{TemplateBinding HeaderTemplateSelector}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}"/>
                </Border>                   
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

And then just click on the the item in the tree view:

My xaml looks like this:

<TreeView Name="x_folderTreeView" Grid.Column="0" ItemsSource="{Binding RootFolderItems}" SelectedItemChanged ="SelectedFolderChangedEx">
<TreeView.ItemTemplate >
<HierarchicalDataTemplate DataType="{x:Type NsUI:NsUICreateObjectFolderItem}" ItemsSource="{Binding ChildFolders}" >
<Grid PreviewMouseLeftButtonDown="Folder_TreeView_ItemSelected" >
<TextBlock Text="{Binding FolderName}" Height="35" FontSize="22"/>
</Grid>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>