WPF TabControl borders not rendering properly in MMC snap-in

Question

I am hosting a WPF TabControl inside of a Windows Form that is part of an MMC snap-in. Everything looks fine on Windows 8.1:

But I have an issue in Windows Server 2012 R2:

From above, you can see that it increases the border of my TabControl. Also, I've noticed other issues in some of my other WPF tab items (things like list view items being vertically aligned to the top instead of the center and stuff like that). But for now, lets address the double-thick borders issue. Why did this happen, and how can I fix it? I have been trying to Google about this issue for hours but I can't seem to find any good workarounds or fixes. Also notice that under the Inbound text, you see the border here as well. Is this not peculiar?

To host a WPF control within a Windows Form, I set the child control of an ElementHost object part of the dialog to a WPF control:

WPFControlHost.Child = new WPFConfigurationTabPageControl(configuration, this);

In my WPF control, I don't do anything special or out of the ordinary. I create my tab control in XAML:

<TabControl Margin="10 10 10 0">
    <TabItem Name="TabItemIdentity" Header="_Identity"/>
    <TabItem Name="TabItemDirectories" Header="_Directories"/>
    <TabItem Name="TabItemRouting" Header="_Routing"/>
    <TabItem Name="TabItemOutbound" Header="O_utbound"/>
    <TabItem Name="TabItemInbound" Header="I_nbound"/>
</TabControl>

Then I set up my tab items in the constructor for my WPF control:

IdentityControl = new WPFIdentityControl(configuration, this);
TabItemIdentity.Content = IdentityControl;
DirectoriesControl = new WPFDirectoriesControl(configuration, this);
TabItemDirectories.Content = DirectoriesControl;
RoutingControl = new WPFRoutingControl(configuration, this);
TabItemRouting.Content = RoutingControl;
OutboundControl = new WPFOutboundControl(configuration, this);
TabItemOutbound.Content = OutboundControl;
InboundControl = new WPFInboundControl(configuration, this);
TabItemInbound.Content = InboundControl;

Edit: When I set 0 thickness on my TabControl (<TabControl Margin="10 10 10 0" BorderThickness="0">), it looks as follows:

So for sure the enlarged borders are being rendered this way as part of just the TabControl control in Windows Server 2012 R2, but why is this? Why are they enlarged, and how can I fix it?

Setting BorderThickness to 1 explicitly fixes the issue of the enlarged borders, but does not fix the header template having a bottom border on itself or the underside of headers having bottom borders at double the size, so I think I need to boot up Blend and edit these templates manually to remove the bottom borders, which is totally insane. Why does this happen on Server 2012?

Answer 1

To fix it I edited the template in Blend. If you've never used Blend for Visual Studio before, now's a chance to get started ("C:\Program Files (x86)\Microsoft Visual Studio 12.0\Blend\Blend.exe"). I used it to change the template of the TabItems. You just right-click, edit template, edit a copy, and it includes most of the markup below which you will need to modify. I changed lots of references of BorderThickness="0,1,1,1" to BorderThickness="1,1,1,0". Here's the markup...

Directly inside of my Window element:

<UserControl.Resources>
    <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>
    <LinearGradientBrush x:Key="TabItem.Static.Background" EndPoint="0,1" StartPoint="0,0">
        <GradientStop Color="#F0F0F0" Offset="0.0"/>
        <GradientStop Color="#E5E5E5" Offset="1.0"/>
    </LinearGradientBrush>
    <SolidColorBrush x:Key="TabItem.Static.Border" Color="#ACACAC"/>
    <LinearGradientBrush x:Key="TabItem.MouseOver.Background" EndPoint="0,1" StartPoint="0,0">
        <GradientStop Color="#ECF4FC" Offset="0.0"/>
        <GradientStop Color="#DCECFC" Offset="1.0"/>
    </LinearGradientBrush>
    <SolidColorBrush x:Key="TabItem.MouseOver.Border" Color="#7EB4EA"/>
    <SolidColorBrush x:Key="TabItem.Disabled.Background" Color="#F0F0F0"/>
    <SolidColorBrush x:Key="TabItem.Disabled.Border" Color="#D9D9D9"/>
    <SolidColorBrush x:Key="TabItem.Selected.Border" Color="#ACACAC"/>
    <SolidColorBrush x:Key="TabItem.Selected.Background" Color="#FFFFFF"/>
    <Style x:Key="TabItemStyle1" TargetType="{x:Type TabItem}">
        <Setter Property="FocusVisualStyle" Value="{StaticResource FocusVisual}"/>
        <Setter Property="Foreground" Value="Black"/>
        <Setter Property="Background" Value="{StaticResource TabItem.Static.Background}"/>
        <Setter Property="BorderBrush" Value="{StaticResource TabItem.Static.Border}"/>
        <Setter Property="Margin" Value="0"/>
        <Setter Property="Padding" Value="6,2,6,2"/>
        <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
        <Setter Property="VerticalContentAlignment" Value="Stretch"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type TabItem}">
                    <Grid x:Name="templateRoot" SnapsToDevicePixels="true">
                        <Border x:Name="mainBorder" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="1,1,1,0" Background="{TemplateBinding Background}" Margin="0">
                            <Border x:Name="innerBorder" BorderBrush="{StaticResource TabItem.Selected.Border}" BorderThickness="1,1,1,0" Background="{StaticResource TabItem.Selected.Background}" Margin="-1" Opacity="0"/>
                        </Border>
                        <ContentPresenter x:Name="contentPresenter" ContentSource="Header" Focusable="False" HorizontalAlignment="{Binding HorizontalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}" Margin="{TemplateBinding Padding}" RecognizesAccessKey="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{Binding VerticalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
                    </Grid>
                    <ControlTemplate.Triggers>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource Self}}" Value="true"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Left"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Background" TargetName="mainBorder" Value="{StaticResource TabItem.MouseOver.Background}"/>
                            <Setter Property="BorderBrush" TargetName="mainBorder" Value="{StaticResource TabItem.MouseOver.Border}"/>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource Self}}" Value="true"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Bottom"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Background" TargetName="mainBorder" Value="{StaticResource TabItem.MouseOver.Background}"/>
                            <Setter Property="BorderBrush" TargetName="mainBorder" Value="{StaticResource TabItem.MouseOver.Border}"/>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource Self}}" Value="true"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Right"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Background" TargetName="mainBorder" Value="{StaticResource TabItem.MouseOver.Background}"/>
                            <Setter Property="BorderBrush" TargetName="mainBorder" Value="{StaticResource TabItem.MouseOver.Border}"/>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource Self}}" Value="true"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Top"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Background" TargetName="mainBorder" Value="{StaticResource TabItem.MouseOver.Background}"/>
                            <Setter Property="BorderBrush" TargetName="mainBorder" Value="{StaticResource TabItem.MouseOver.Border}"/>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="false"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Left"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Opacity" TargetName="contentPresenter" Value="0.56"/>
                            <Setter Property="Background" TargetName="mainBorder" Value="{StaticResource TabItem.Disabled.Background}"/>
                            <Setter Property="BorderBrush" TargetName="mainBorder" Value="{StaticResource TabItem.Disabled.Border}"/>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="false"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Bottom"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Opacity" TargetName="contentPresenter" Value="0.56"/>
                            <Setter Property="Background" TargetName="mainBorder" Value="{StaticResource TabItem.Disabled.Background}"/>
                            <Setter Property="BorderBrush" TargetName="mainBorder" Value="{StaticResource TabItem.Disabled.Border}"/>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="false"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Right"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Opacity" TargetName="contentPresenter" Value="0.56"/>
                            <Setter Property="Background" TargetName="mainBorder" Value="{StaticResource TabItem.Disabled.Background}"/>
                            <Setter Property="BorderBrush" TargetName="mainBorder" Value="{StaticResource TabItem.Disabled.Border}"/>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="false"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Top"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Opacity" TargetName="contentPresenter" Value="0.56"/>
                            <Setter Property="Background" TargetName="mainBorder" Value="{StaticResource TabItem.Disabled.Background}"/>
                            <Setter Property="BorderBrush" TargetName="mainBorder" Value="{StaticResource TabItem.Disabled.Border}"/>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="false"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Left"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="true"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Left"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Panel.ZIndex" Value="1"/>
                            <Setter Property="Margin" Value="-2,-2,0,-2"/>
                            <Setter Property="Opacity" TargetName="innerBorder" Value="1"/>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="false"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Bottom"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="true"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Bottom"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Panel.ZIndex" Value="1"/>
                            <Setter Property="Margin" Value="-2,0,-2,-2"/>
                            <Setter Property="Opacity" TargetName="innerBorder" Value="1"/>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="false"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Right"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="true"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Right"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Panel.ZIndex" Value="1"/>
                            <Setter Property="Margin" Value="0,-2,-2,-2"/>
                            <Setter Property="Opacity" TargetName="innerBorder" Value="1"/>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="false"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Top"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="true"/>
                                <Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource AncestorType={x:Type TabControl}}}" Value="Top"/>
                            </MultiDataTrigger.Conditions>
                            <Setter Property="Panel.ZIndex" Value="1"/>
                            <Setter Property="Margin" Value="-2,-2,-2,0"/>
                            <Setter Property="Opacity" TargetName="innerBorder" Value="1"/>
                            <Setter Property="BorderThickness" TargetName="innerBorder" Value="1,1,1,0"/>
                            <Setter Property="BorderThickness" TargetName="mainBorder" Value="1,1,1,0"/>
                        </MultiDataTrigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</UserControl.Resources>

And for my TabControl:

<TabControl Margin="10 10 10 0" BorderThickness="1">
    <TabItem Name="TabItemIdentity" Header="_Identity" Style="{DynamicResource TabItemStyle1}"/>
    <TabItem Name="TabItemDirectories" Header="_Directories" Style="{DynamicResource TabItemStyle1}"/>
    <TabItem Name="TabItemRouting" Header="_Routing" Style="{DynamicResource TabItemStyle1}"/>
    <TabItem Name="TabItemOutbound" Header="O_utbound" Style="{DynamicResource TabItemStyle1}"/>
    <TabItem Name="TabItemInbound" Header="I_nbound" Style="{DynamicResource TabItemStyle1}"/>
</TabControl>

Nightmarish.

Edit: On Windows Server 2008 R2 (another catastrophe), you will need to set the background explicitly for controls since it does not support transparency and will default to the default forms background color for controls when Background="Transparent" is set for any control's style properties, so you should explicitly set the control background as white on your controls if they don't render properly (for example, <TabControl Margin="10 10 10 0" BorderThickness="1" Background="White">). Also, I strongly suggest you edit your template in Blend for the TabControl and apply it locally (<TabControl Margin="10 10 10 0" BorderThickness="1" Background="White" Style="{DynamicResource TabControlStyle1}"), so apply the default template here and package it locally as part of your application DLL and you should be fine. For some reason, it does not render the template properly in Windows Server 2008 R2 unless its a dynamic resource that is part of the same DLL. Perhaps this is because I have set the COMPLUS_Version environment variable to make MMC work with .NET Framework 4.5, whereas it might have been trying to use an older template from a previous version of the .NET Framework.