Question

I’m quite new to WPF. I just try some layouting with Grid and Listbox,
but I have some padding / spacing / margin / border (just call it border
for shortness) that I can not get away.

The border is around the four elements, the elements themselves have no problems
and there is no space between them.

Also tried the WPF Inspector, but I can’t find out where this comes from.
Nothing to see in it.

Here is my XAML:

<Window x:Class="WpfElements.FourElements"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="FourElements" Height="701" Width="351">
<Grid Background="Red" Margin="0" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
    <Grid.RowDefinitions>
        <RowDefinition Height="*" />
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*" />
    </Grid.ColumnDefinitions>

    <ListBox Margin="0" BorderThickness="0" Padding="0" Grid.Row="0" Grid.Column="0" Background="Lime" SelectionMode="Single" ItemsSource="{Binding Path=Texts}" ScrollViewer.HorizontalScrollBarVisibility="Disabled" ScrollViewer.VerticalScrollBarVisibility="Disabled" VerticalContentAlignment="Stretch" HorizontalContentAlignment="Stretch">
        <ListBox.ItemsPanel>
            <ItemsPanelTemplate>
                <Grid HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Margin="0">
                    <Grid.RowDefinitions>
                        <RowDefinition Height="*" />
                        <RowDefinition Height="*" />
                    </Grid.RowDefinitions>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="*" />
                        <ColumnDefinition Width="*" />
                    </Grid.ColumnDefinitions>
                </Grid>
            </ItemsPanelTemplate>
        </ListBox.ItemsPanel>
        <ListBox.ItemTemplate>
            <DataTemplate>
                <TextBox Text="{Binding ItemText}" Grid.Row="{Binding Path=Row}" Grid.Column="{Binding Path=Col}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Margin="0"></TextBox>
            </DataTemplate>
        </ListBox.ItemTemplate>
        <ListBox.ItemContainerStyle>
            <Style>
                <Setter Property="Grid.Column" Value="{Binding Path=Col}"/>
                <Setter Property="Grid.Row" Value="{Binding Path=Row}"/>
                <Setter Property="ContentControl.HorizontalContentAlignment" Value="Stretch"/>
                <Setter Property="ContentControl.VerticalContentAlignment" Value="Stretch"/>
                <Setter Property="ContentControl.Margin" Value="0"/>
                <Setter Property="ContentControl.Padding" Value="0"/>
                <Setter Property="Control.BorderThickness" Value="0"/>
            </Style>
        </ListBox.ItemContainerStyle>
    </ListBox>
</Grid>

Hope someone can help me get rid of this border. Thank you so much!

Answer 1

The problem is the first Border inside the ListBox Template, it has Padding set to 1,1,1,1.
It looks like this

<Style TargetType="{x:Type ListBox}" ...>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type ListBox}">
                <Border x:Name="Bd"
                        Padding="1">
                <!-- ... -->

As you can see in the Template, the Border name is Bd.

Either change the Template for the ListBox or set it to 0 in the Loaded event

Xaml

<ListBox ...
         Loaded="ListBox_Loaded">

Code behind

private void ListBox_Loaded(object sender, RoutedEventArgs e)
{
    ListBox listBox = sender as ListBox;
    Border Bd = listBox.Template.FindName("Bd", listBox) as Border;
    Bd.Padding = new Thickness(0);
}