Prevent background bleed through on WPF textbox

Question

<Page
x:Class="MDC.Inspect.View.BlankPage1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">

<Grid Background="#FF1F3830">
    <TextBox Background="Black"
             Margin="50"
             Opacity="1" />
</Grid>
</Page>

Simple code to demonstrate my issue, the background of the textbox is set to black, it is definitely not rendered as black, I see #13221D

How can I prevent this "bleed through" of the grid background into my textbox's background, as it happens with all colors. It looks like it has something to do with focused vs unfocused, but I don't know what properties those would be.

Answer 1

Using VS 2015, in the Document Outline window, right click the textbox and select "Edit Template"->"Edit a Copy...". Pick your options and click OK.

In the generated template, you will see the VisualState "PointerOver". It looks like this:

<VisualState x:Name="PointerOver">
    <Storyboard>
        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="BorderElement">
            <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightChromeAltLowBrush}"/>
        </ObjectAnimationUsingKeyFrames>
        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Opacity" Storyboard.TargetName="BackgroundElement">
            <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlBackgroundHoverOpacity}"/>
        </ObjectAnimationUsingKeyFrames>
    </Storyboard>
</VisualState>

It sets BorderElement.BorderBrush and BackgroundElement.Opacity. We really only care about the BackgroundElement.Opacity. BTW, {ThemeResource TextControlBackgroundHoverOpacity} for the light theme is 0.6.

Scroll down a little further in the template and you will find BackgroundElement:

<Border x:Name="BackgroundElement" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" Margin="{TemplateBinding BorderThickness}" Opacity="{ThemeResource TextControlBackgroundRestOpacity}" Grid.Row="1" Grid.RowSpan="1"/>

So, the initial opacity is set to {ThemeResource TextControlBackgroundRestOpacity}, which is 0.4 in the light theme.

If you always want it to be at full opacity, set them both (initial and PointerOver) to TextControlBackgroundFocusedOpacity (which is 1 in the light theme).

EDIT Here is the entire Style:

<Style x:Key="TextBoxStyle1" TargetType="TextBox">
    <Setter Property="MinWidth" Value="{ThemeResource TextControlThemeMinWidth}"/>
    <Setter Property="MinHeight" Value="{ThemeResource TextControlThemeMinHeight}"/>
    <Setter Property="Foreground" Value="{ThemeResource SystemControlForegroundBaseHighBrush}"/>
    <Setter Property="Background" Value="{ThemeResource SystemControlBackgroundAltHighBrush}"/>
    <Setter Property="BorderBrush" Value="{ThemeResource SystemControlForegroundChromeDisabledLowBrush}"/>
    <Setter Property="SelectionHighlightColor" Value="{ThemeResource SystemControlHighlightAccentBrush}"/>
    <Setter Property="BorderThickness" Value="{ThemeResource TextControlBorderThemeThickness}"/>
    <Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}"/>
    <Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}"/>
    <Setter Property="ScrollViewer.HorizontalScrollMode" Value="Auto"/>
    <Setter Property="ScrollViewer.VerticalScrollMode" Value="Auto"/>
    <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Hidden"/>
    <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Hidden"/>
    <Setter Property="ScrollViewer.IsDeferredScrollingEnabled" Value="False"/>
    <Setter Property="Padding" Value="{ThemeResource TextControlThemePadding}"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="TextBox">
                <Grid>
                    <Grid.Resources>
                        <Style x:Name="DeleteButtonStyle" TargetType="Button">
                            <Setter Property="Template">
                                <Setter.Value>
                                    <ControlTemplate TargetType="Button">
                                        <Grid x:Name="ButtonLayoutGrid" BorderBrush="{ThemeResource TextBoxButtonBorderThemeBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{ThemeResource TextBoxButtonBackgroundThemeBrush}">
                                            <VisualStateManager.VisualStateGroups>
                                                <VisualStateGroup x:Name="CommonStates">
                                                    <VisualState x:Name="Normal"/>
                                                    <VisualState x:Name="PointerOver">
                                                        <Storyboard>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="GlyphElement">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAccentBrush}"/>
                                                            </ObjectAnimationUsingKeyFrames>
                                                        </Storyboard>
                                                    </VisualState>
                                                    <VisualState x:Name="Pressed">
                                                        <Storyboard>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="ButtonLayoutGrid">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAccentBrush}"/>
                                                            </ObjectAnimationUsingKeyFrames>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="GlyphElement">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltChromeWhiteBrush}"/>
                                                            </ObjectAnimationUsingKeyFrames>
                                                        </Storyboard>
                                                    </VisualState>
                                                    <VisualState x:Name="Disabled">
                                                        <Storyboard>
                                                            <DoubleAnimation Duration="0" To="0" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="ButtonLayoutGrid"/>
                                                        </Storyboard>
                                                    </VisualState>
                                                </VisualStateGroup>
                                            </VisualStateManager.VisualStateGroups>
                                            <TextBlock x:Name="GlyphElement" AutomationProperties.AccessibilityView="Raw" Foreground="{ThemeResource SystemControlForegroundChromeBlackMediumBrush}" FontStyle="Normal" FontSize="12" FontFamily="{ThemeResource SymbolThemeFontFamily}" HorizontalAlignment="Center" Text="&#xE10A;" VerticalAlignment="Center"/>
                                        </Grid>
                                    </ControlTemplate>
                                </Setter.Value>
                            </Setter>
                        </Style>
                    </Grid.Resources>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="*"/>
                        <ColumnDefinition Width="Auto"/>
                    </Grid.ColumnDefinitions>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="Auto"/>
                        <RowDefinition Height="*"/>
                    </Grid.RowDefinitions>
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="CommonStates">
                            <VisualState x:Name="Disabled">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="HeaderContentPresenter">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledBaseMediumLowBrush}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="BackgroundElement">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledTransparentBrush}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="BorderElement">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlBackgroundBaseLowBrush}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="BorderElement">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledBaseLowBrush}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="ContentElement">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledChromeDisabledLowBrush}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="PlaceholderTextContentPresenter">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledChromeDisabledLowBrush}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="Normal"/>
                            <VisualState x:Name="PointerOver">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="BorderElement">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightChromeAltLowBrush}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Opacity" Storyboard.TargetName="BackgroundElement">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlBackgroundHoverOpacity}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="Focused">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="PlaceholderTextContentPresenter">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlPageTextChromeBlackMediumLowBrush}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="BackgroundElement">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlBackgroundChromeWhiteBrush}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Opacity" Storyboard.TargetName="BackgroundElement">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlBackgroundFocusedOpacity}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="BorderElement">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAccentBrush}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="ContentElement">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlForegroundChromeBlackHighBrush}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="RequestedTheme" Storyboard.TargetName="ContentElement">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="Light"/>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                        </VisualStateGroup>
                        <VisualStateGroup x:Name="ButtonStates">
                            <VisualState x:Name="ButtonVisible">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="DeleteButton">
                                        <DiscreteObjectKeyFrame KeyTime="0">
                                            <DiscreteObjectKeyFrame.Value>
                                                <Visibility>Visible</Visibility>
                                            </DiscreteObjectKeyFrame.Value>
                                        </DiscreteObjectKeyFrame>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="ButtonCollapsed"/>
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <Border x:Name="BackgroundElement" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" Margin="{TemplateBinding BorderThickness}" Opacity="{ThemeResource TextControlBackgroundRestOpacity}" Grid.Row="1" Grid.RowSpan="1"/>
                    <Border x:Name="BorderElement" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Grid.ColumnSpan="2" Grid.Row="1" Grid.RowSpan="1"/>
                    <ContentPresenter x:Name="HeaderContentPresenter" Grid.ColumnSpan="2" ContentTemplate="{TemplateBinding HeaderTemplate}" Content="{TemplateBinding Header}" Foreground="{ThemeResource SystemControlForegroundBaseHighBrush}" FontWeight="Normal" Margin="0,0,0,8" Grid.Row="0" Visibility="Collapsed" x:DeferLoadStrategy="Lazy"/>
                    <ScrollViewer x:Name="ContentElement" AutomationProperties.AccessibilityView="Raw" HorizontalScrollMode="{TemplateBinding ScrollViewer.HorizontalScrollMode}" HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}" IsTabStop="False" IsHorizontalRailEnabled="{TemplateBinding ScrollViewer.IsHorizontalRailEnabled}" IsVerticalRailEnabled="{TemplateBinding ScrollViewer.IsVerticalRailEnabled}" IsDeferredScrollingEnabled="{TemplateBinding ScrollViewer.IsDeferredScrollingEnabled}" Margin="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}" Grid.Row="1" VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}" VerticalScrollMode="{TemplateBinding ScrollViewer.VerticalScrollMode}" ZoomMode="Disabled"/>
                    <ContentControl x:Name="PlaceholderTextContentPresenter" Grid.ColumnSpan="2" Content="{TemplateBinding PlaceholderText}" Foreground="{ThemeResource SystemControlPageTextBaseMediumBrush}" IsHitTestVisible="False" IsTabStop="False" Margin="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}" Grid.Row="1"/>
                    <Button x:Name="DeleteButton" BorderThickness="{TemplateBinding BorderThickness}" Grid.Column="1" FontSize="{TemplateBinding FontSize}" IsTabStop="False" Margin="{ThemeResource HelperButtonThemePadding}" MinWidth="34" Grid.Row="1" Style="{StaticResource DeleteButtonStyle}" Visibility="Collapsed" VerticalAlignment="Stretch"/>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>