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Customizing ScrollViewer Style breaks RichTextBox Mouse Wheel Scrolling

To reproduce this, simply add this style to any wpf project that has a RichTextBox:
https://pastebin.com/dJAqFC3d
And a full minimal project can be located here:
https://drive.google.com/file/d/1a7e-vwKpt1Emg7fhMhVRLccwrjOlhWk1/view?usp=sharing
Also an example of the two styles:
<!--
This style does NOT break RichTextBox Scrolling
-->
<Style TargetType="{x:Type ScrollViewer}">
<Style.Resources>
<SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}" Color="Transparent" />
</Style.Resources>
</Style>
<!--
The Style below breaks Rich Text Box
-->
<!--<Style TargetType="{x:Type ScrollViewer}">
<Setter Property="CanContentScroll" Value="True"></Setter>
<Setter Property="PanningMode" Value="Both"></Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ScrollViewer}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<ScrollContentPresenter Grid.Column="0" />
<ScrollBar
x:Name="PART_VerticalScrollBar"
Grid.Row="0"
Grid.Column="1"
Maximum="{TemplateBinding ScrollableHeight}"
ViewportSize="{TemplateBinding ViewportHeight}"
Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}"
Value="{TemplateBinding VerticalOffset}" />
<ScrollBar
x:Name="PART_HorizontalScrollBar"
Grid.Row="1"
Grid.Column="0"
Maximum="{TemplateBinding ScrollableWidth}"
Orientation="Horizontal"
ViewportSize="{TemplateBinding ViewportWidth}"
Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}"
Value="{TemplateBinding HorizontalOffset}" />
--><!--<Rectangle Grid.Row="1" Grid.Column="1" Fill="Red"/>--><!--
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>-->
Then at the bottom of the style, comment out either of the ScrollViewer styles to swap between them. One simply overrides the bottom right rectangle color. The other does the same, but also defines the scrollbars. The style that defines the scrollbars breaks vertical scrolling.
This can also be reproduced using the official Microsoft provided styles, located here:
https://learn.microsoft.com/en-us/dotnet/desktop/wpf/controls/scrollbar-styles-and-templates?view=netframeworkdesktop-4.8
and here
https://learn.microsoft.com/en-us/dotnet/desktop/wpf/controls/scrollviewer-styles-and-templates?view=netframeworkdesktop-4.8
UPDATE: (The above links will soon be an invalid example, because this issue has been submitted, and it is apparently going to be addressed and fixed)
Does anyone know why declaring a custom style for ScrollViewers breaks RichTextBox mouse wheel scrolling?
Edit: It should also be noted that the above example does not hinder or break the vertical mouse wheel scrolling of any other control (that I've noticed). RichTextBox seems to be an edge case.

Found the solution, and it's actually stupid easy.
You have to add CanContentScroll="True" to the ScrollContentPresenter within the ScrollViewer control template. Here is an example:
<Style TargetType="{x:Type ScrollViewer}">
<Setter Property="CanContentScroll" Value="True"></Setter>
<Setter Property="PanningMode" Value="Both"></Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ScrollViewer}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<ScrollContentPresenter CanContentScroll="True" Grid.Column="0" />
<ScrollBar
x:Name="PART_VerticalScrollBar"
Grid.Row="0"
Grid.Column="1"
Maximum="{TemplateBinding ScrollableHeight}"
ViewportSize="{TemplateBinding ViewportHeight}"
Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}"
Value="{TemplateBinding VerticalOffset}" />
<ScrollBar
x:Name="PART_HorizontalScrollBar"
Grid.Row="1"
Grid.Column="0"
Maximum="{TemplateBinding ScrollableWidth}"
Orientation="Horizontal"
ViewportSize="{TemplateBinding ViewportWidth}"
Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}"
Value="{TemplateBinding HorizontalOffset}" />
<Rectangle Grid.Row="1" Grid.Column="1" Fill="Red"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
This is not mentioned anywhere within the microsoft style example, and they also ommit it from their suggested style template.

Border is added only to the first text block in WPF

Edit : I realized what the problem is, when I add the border, The second TextBlock sits on top of the first TextBlock. Still have to figure out why this is happening.
Original question:
I have a number of TextBlocks in my xaml. I want to add a border around some textblocks. I tried the following methods.
Method 1:
<Style x:Key="BorderForTextBlock" TargetType="{x:Type Border}">
<Setter Property="BorderThickness" Value="1" />
<Setter Property="BorderBrush" Value="Black" />
</Style>
<TextBlock1../>
<Border Style="{StaticResource BorderForTextBlock}">
<TextBlock2.../>
</Border>
Method 2:
<TextBlock1../> //This is where the border is added.
<Border BorderThickness="1" BorderBrush="Black">
<TextBlock2 ..../> //This is where I want to add the border
</Border>
A border is added only to the first TextBlock in the xaml no matter to which TextBlock I add the border. I don't want the border on the first TextBlock. I have no clue why this is happening.
This is my xaml :
<Grid Background="LightYellow" >
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" ></ColumnDefinition>
<ColumnDefinition Width="3.5*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="28*" ></RowDefinition>
<RowDefinition Height="120*" ></RowDefinition>
<RowDefinition Height="28*"></RowDefinition>
<RowDefinition Height="74*"></RowDefinition>
</Grid.RowDefinitions>
<TextBlock Grid.Row="0" Margin="10,0,5,0" FontWeight="SemiBold" Text="{x:Static res:Resources.source1"/>
<Border BorderBrush="Black" BorderThickness="1">
<TextBlock x:Name="txtBlock1" FormatTest:FormattedTextBehavior.FormattedText="{Binding Path= content1}" Margin="0,0,0,0" Grid.Row="0" Grid.Column="1" TextWrapping="Wrap"/>
</Border>
<TextBlock Grid.Row="1" Margin="10,0,5,0" FontWeight="SemiBold" Text="{x:Static res:Resources.source2}"/>
<RichTextBox Background="LightYellow" Margin="0,0,0,0" ScrollViewer.HorizontalScrollBarVisibility="Auto" ScrollViewer.VerticalScrollBarVisibility="Auto" ScrollViewer.CanContentScroll="True" Grid.Row="1" Grid.Column="1" IsReadOnly="True" >
<FlowDocument>
<Paragraph>
<Run Text="{Binding content2, Mode=TwoWay}"/>
</Paragraph>
</FlowDocument>
</RichTextBox>
<TextBlock Grid.Row="2" Margin="10,0,5,0" FontWeight="SemiBold" Text="{x:Static res:Resources.source3"/>
<TextBlock Text="{Binding content3, Mode=TwoWay}" Margin="0,0,0,0" Grid.Row="2" Grid.Column="1" ScrollViewer.HorizontalScrollBarVisibility="Auto" ScrollViewer.VerticalScrollBarVisibility="Auto" ScrollViewer.CanContentScroll="True" TextWrapping="Wrap"/>
<TextBlock Grid.Row="3" Margin="10,0,5,0" FontWeight="SemiBold" Text="{x:Static res:Resources.source4}"/>
<TextBox Text="{Binding content4, Mode=TwoWay}" Margin="0,0,0,0" Grid.Row="3" Grid.Column="1" ScrollViewer.HorizontalScrollBarVisibility="Auto" ScrollViewer.VerticalScrollBarVisibility="Auto"
ScrollViewer.CanContentScroll="True" TextAlignment="Left" TextWrapping="Wrap" Background="LightYellow" IsReadOnly="True"/>
</Grid>

instead of
<Border BorderBrush="Black" BorderThickness="1">
<TextBlock x:Name="txtBlock1" FormatTest:FormattedTextBehavior.FormattedText="{Binding Path= content1}" Margin="0,0,0,0" Grid.Row="0" Grid.Column="1" TextWrapping="Wrap"/>
</Border>
Have
<Border Grid.Row="0" Grid.Column="1" BorderBrush="Black" BorderThickness="1">
<TextBlock x:Name="txtBlock1" FormatTest:FormattedTextBehavior.FormattedText="{Binding Path= content1}" Margin="0,0,0,0" TextWrapping="Wrap"/>
</Border>
This should solve the issue with placement of text blocks
This is how it looks at my end
Try this and let us know

You can use style with trigger and put the style either in windows resources or app resources depending upon scope you want
<Window x:Class="WpfApplication2.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
<Grid.Resources>
<Style x:Key="NotCalledBorder" TargetType="{x:Type Border}">
<Setter Property="BorderThickness" Value="1" />
<Setter Property="BorderBrush" Value="Black" />
<Setter Property="Height" Value="20"/>
<Setter Property="Width" Value="30"/>
<Setter Property="HorizontalAlignment" Value="Left"/>
</Style>
<Style TargetType="TextBlock">
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="TextDecorations" Value="Underline" />
</Trigger>
</Style.Triggers>
</Style>
</Grid.Resources>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<Border Style="{StaticResource NotCalledBorder}" Grid.Row="0">
<TextBlock Text="test1" Grid.Row="0" OpacityMask="Black">
</TextBlock>
</Border>
<TextBlock Text="test2" Grid.Row="1"></TextBlock>
<Border Style="{StaticResource NotCalledBorder}" Grid.Row="2">
<TextBlock Text="test3" Grid.Row="2" OpacityMask="Black"></TextBlock>
</Border>
<TextBlock Text="test4" Grid.Row="3"></TextBlock>
</Grid>
</Window>
Conditional style in WPF. Adding border to two textblocks only. You can apply style and add to as many as you want

Margin difference in nested ListBox with DataTemplates

I have a problem with my ListBox. I have written several DataTemplates which I use in a ListBox. Each one of these contains a grid and may contain a nested ListBox depending on the item.
My problem is: The height of these nested ListBoxes seem to be different to the root ListBox's height. Additionally it seems, that there is sometimes one pixel margin to the element above.
Has someone encountered this problem, too and maybe solved it?
XAML-Code:
<!-- Template for SubData-Items -->
<DataTemplate x:Key="DataTemplate">
<Grid x:Name="baseGrid" Grid.Column="0" Grid.ColumnSpan="999" Background="Violet">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="{Binding ElementName=Col0, Path=Width}" />
<ColumnDefinition Width="{Binding ElementName=Col1, Path=Width}" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="{Binding ElementName=Row0, Path=Height}"/>
</Grid.RowDefinitions>
<TextBlock Grid.Column="1" Text="{Binding Bezeichnung}" HorizontalAlignment="Left" VerticalAlignment="Center" FontSize="12" />
<Line Grid.ColumnSpan="999" Stroke="Black" X1="0" X2="{Binding ElementName=baseGrid, Path=ActualWidth, Mode=OneWay}" Y1="0" Y2="0" VerticalAlignment="Bottom" />
</Grid>
</DataTemplate>
<!-- Template for Items -->
<DataTemplate x:Key="GroupDataTemplate">
<Grid Grid.ColumnSpan="999" Background="Blue">
<Grid.RowDefinitions>
<RowDefinition Height="{Binding ElementName=Gantt, Path=GridRowHeight}" />
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid x:Name="baseGrid" Grid.Column="0" Grid.ColumnSpan="999">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="{Binding ElementName=Col0, Path=Width}" />
<ColumnDefinition Width="{Binding ElementName=Col1, Path=Width}" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="{Binding ElementName=Row0, Path=Height}"/>
</Grid.RowDefinitions>
<TextBlock Grid.Column="1" Text="{Binding Bezeichnung}" HorizontalAlignment="Left" VerticalAlignment="Center" FontSize="12" />
</Grid>
<Grid x:Name="expandedGrid" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="999">
<ListBox x:Name="LBMaGruppen" ItemTemplate="{StaticResource DataTemplate}" ItemsSource="{Binding SubdataObjects}"
VerticalAlignment="Stretch" HorizontalAlignment="Stretch" HorizontalContentAlignment="Stretch" Height="Auto" Margin="0,0,2,0"
ScrollViewer.CanContentScroll="false" ScrollViewer.HorizontalScrollBarVisibility="Disabled" ScrollViewer.VerticalScrollBarVisibility="Disabled" BorderThickness="0" />
</Grid>
</Grid>
</DataTemplate>
<!-- Grid with ListBox -->
<Grid>
<Grid.RowDefinitions>
<RowDefinition x:Name="Row0" Height="34"/>
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition x:Name="Col0" Width="25" />
<ColumnDefinition x:Name="Col1" Width="*" />
</Grid.ColumnDefinitions>
<ListBox Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="999" ItemsSource="{Binding ItemSource, Mode=OneWay}"
ItemTemplate="{StaticResource GroupDataTemplate}"
VerticalAlignment="Stretch" HorizontalAlignment="Stretch" Height="Auto"
ScrollViewer.CanContentScroll="true"
ScrollViewer.IsDeferredScrollingEnabled="False"
ScrollViewer.HorizontalScrollBarVisibility="Disabled"
ScrollViewer.VerticalScrollBarVisibility="Disabled"
FontSize="10" />
</Grid>

qqbenq gave a very nice solution . Here is another way to do it.
the control templates of ListBox and ListBoxItem has padding inside their borders. Thankfully ListBoxItem border's padding can be control by a style like so:
<Style
TargetType="ListBoxItem">
<Setter
Property="Padding"
Value="0" />
</Style>
but unfortunately for the ListBox , you will have to override the default template with all of its details to change its internal border's hard-coded padding like this:
<Style
TargetType="ListBox">
<Setter
Property="Template">
<Setter.Value>
<ControlTemplate
TargetType="{x:Type ListBox}">
<Border
x:Name="Bd"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}"
Padding="0"
SnapsToDevicePixels="true">
<ScrollViewer
Focusable="false"
Padding="{TemplateBinding Padding}">
<ItemsPresenter
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
</ScrollViewer>
</Border>
<ControlTemplate.Triggers>
<Trigger
Property="IsEnabled"
Value="false">
<Setter
Property="Background"
TargetName="Bd"
Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}" />
</Trigger>
<Trigger
Property="IsGrouping"
Value="true">
<Setter
Property="ScrollViewer.CanContentScroll"
Value="false" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
One last note : remove the Margin that you added inside your xaml.
Solution complete

Add a Margin="-2,0,0,0" and a Padding="-1" to your "LBMaGruppen" named ListBox.
<ListBox x:Name="LBMaGruppen" ItemTemplate="{StaticResource DataTemplate}" ItemsSource="{Binding SubdataObjects}"
VerticalAlignment="Stretch" HorizontalAlignment="Stretch" HorizontalContentAlignment="Stretch" Height="Auto" Margin="-2,0,0,0" Padding="-1"
ScrollViewer.CanContentScroll="false" ScrollViewer.HorizontalScrollBarVisibility="Disabled" ScrollViewer.VerticalScrollBarVisibility="Disabled" BorderThickness="0" />
Also, the "root" element's height is binded to {Binding ElementName=Gantt, Path=GridRowHeight}, while the "sub" element's height to {Binding ElementName=Row0, Path=Height}, so this must cause the difference.

It seems that you have auto height set on all your ListBox. You could try setting the height to a specific size. EDIT: I see you already have ScrollViewer settings. I think setting the height of the box to a specific size instead of auto will do what you want.
As to the padding between elements see the ListBox.ItemContainerSyle which should allow you to set the margin between elements.

List view Repeat Button Hight and width customization

I am trying to apply style for scroll bars of listview control in WPF.
I want to change height and width of the repeat button.
How can I configure this.
I am newbie in WPF can any one help me out in this topic.
Thanks in Advance.

You'll need to modify the default ScrollBar control template. Copy-paste the default style from here, and modify the "HorizontalIncrementTemplate" and "VerticalIncrementTemplate" XAML as needed (in particular for your case, look at modifying the height/width of the Path elements).
Alternatively, you can also use Blend to modify control templates, which you may find easier.

Try this
<ListView>
<ListView.Style>
<Style TargetType="ListView">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ListView">
<ScrollViewer>
<ScrollViewer.Style>
<Style TargetType="ScrollViewer">
<Setter Property="OverridesDefaultStyle" Value="True"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ScrollViewer">
<!--Grid used for displaying listview item(ScrollContentPresenter Grid.ColumnSpan="2") and vertical scrollviwer(Grid Column="1")-->
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<!--Listview item will display in ScrollContentPresenter-->
<ScrollContentPresenter Grid.ColumnSpan="2"/>
<!--Vertical Scrollviwer style-->
<ScrollBar Name="PART_VerticalScrollBar" Grid.Column="1" HorizontalAlignment="Right" Grid.RowSpan="2" Value="{TemplateBinding VerticalOffset}" Maximum="{TemplateBinding ScrollableHeight}" ViewportSize="{TemplateBinding ViewportHeight}" Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}">
<ScrollBar.Style>
<Style TargetType="ScrollBar">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ScrollBar">
<!--you can change height and width of below repeat button -->
<Grid Background="Green">
<Grid.RowDefinitions>
<RowDefinition MaxHeight="18"/>
<RowDefinition Height="0.00001*"/>
<RowDefinition MaxHeight="18"/>
</Grid.RowDefinitions>
<Border Grid.RowSpan="3" CornerRadius="2" Background="#F0F0F0" />
<RepeatButton Grid.Row="0" Height="0" Command="ScrollBar.LineUpCommand" Content="M 0 4 L 8 4 L 4 0 Z" />
<Track Name="PART_Track" Grid.RowSpan="3" IsDirectionReversed="true">
<Track.DecreaseRepeatButton>
<RepeatButton Height="0" Command="ScrollBar.PageUpCommand" />
</Track.DecreaseRepeatButton>
<Track.Thumb>
<Thumb Background="LightGray" Margin="2" />
</Track.Thumb>
<Track.IncreaseRepeatButton>
<RepeatButton Height="0" Command="ScrollBar.PageDownCommand" />
</Track.IncreaseRepeatButton>
</Track>
<RepeatButton Grid.Row="3" Height="0" Command="ScrollBar.LineDownCommand" Content="M 0 0 L 4 4 L 8 0 Z"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ScrollBar.Style>
</ScrollBar>
<!--similarly you can customize for horizontal scrollviwer-->
<ScrollBar Name="PART_HorizontalScrollBar" Orientation="Horizontal" Grid.Row="1" Grid.Column="1" Value="{TemplateBinding HorizontalOffset}" Maximum="{TemplateBinding ScrollableWidth}" ViewportSize="{TemplateBinding ViewportWidth}" Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ScrollViewer.Style>
<ItemsPresenter></ItemsPresenter>
</ScrollViewer>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ListView.Style>
</ListView>
For more details visit

XAML Listbox alignment issue

I have a Windows Phone 8 page with Country Names on left and ISD codes on right. I want to align the country name to the extreme left and ISD code to the extreme right of the screen.
For this, I wrote the following XAML
<Grid x:Name="LayoutRoot" Background="Transparent">
<ListBox ItemsSource="{Binding IsdCodes}" HorizontalAlignment="Stretch" Background="Blue">
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem">
<Setter Property="HorizontalAlignment" Value="Stretch"/>
</Style>
</ListBox.ItemContainerStyle>
<ListBox.ItemTemplate>
<DataTemplate>
<Grid HorizontalAlignment="Stretch" Background="Yellow" ShowGridLines="True">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="3*"/>
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<TextBox Grid.Column="0" HorizontalAlignment="Stretch" Text="{Binding Key}" />
<TextBox Grid.Column="1" HorizontalAlignment="Stretch" Text="{Binding Value}" />
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
But the output I am getting is as follows :
As I gave the grid column widths as 3* and *, I expected first column to occupy 75% of the width of the screen on left and 2nd column to occupy 25% of the width of the screen on the right. But I do see that listbox item still doesn't occupy the entire screen width (Assumed from the yellow background).
Where did I go wrong?

Try setting HorizontalContentAlignment for ListBoxItem to Stretch:
<Style TargetType="ListBoxItem">
<Setter Property="HorizontalContentAlignment" Value="Stretch"/>
</Style>

This is because the DataTemplate is rendered in a ContentPresenter, which is not stretched in the ListBoxItem. You need to redefine the template for the ListBoxItem:
...
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem">
<Setter Property="HorizontalAlignment" Value="Stretch"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ListBoxItem">
<Border Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
<ContentPresenter HorizontalAlignment="Stretch" />
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ListBox.ItemContainerStyle>
...

As you know width of screen is 480 you could assign it 360 and 120
<ListBox.ItemTemplate>
<DataTemplate>
<Grid HorizontalAlignment="Stretch" Background="Yellow" ShowGridLines="True">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="360"/>
<ColumnDefinition Width="120" />
</Grid.ColumnDefinitions>
<TextBox Grid.Column="0" HorizontalAlignment="Stretch" Text="{Binding Key}" />
<TextBox Grid.Column="1" HorizontalAlignment="Stretch" Text="{Binding Value}" />
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>

This would help you, set width of grid inside listbox datatemplete
<Grid x:Name="LayoutRoot" Background="Transparent">
<ListBox ItemsSource="{Binding IsdCodes}" HorizontalAlignment="Stretch" Background="Blue">
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem">
<Setter Property="HorizontalAlignment" Value="Stretch"/>
</Style>
</ListBox.ItemContainerStyle>
<ListBox.ItemTemplate>
<DataTemplate>
<Grid HorizontalAlignment="Left" Background="Yellow" ShowGridLines="True" Width="460">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<TextBox Grid.Column="0" HorizontalAlignment="Stretch" Text="{Binding Key}" />
<TextBox Grid.Column="1" HorizontalAlignment="Stretch" Text="{Binding Value}" />
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>