StTest/MyTests/Pages/TestPage.xaml

<Page x:Class="MyTests.Pages.TestPage"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
      xmlns:local="clr-namespace:MyTests.Pages"
      mc:Ignorable="d" 
      d:DesignHeight="450" 
      d:DesignWidth="800">
    <Grid Background="{StaticResource color1}">
        <Grid.RowDefinitions>
            <RowDefinition Height="50"/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <StackPanel Orientation="Horizontal"
                    HorizontalAlignment="Left">
            <Image Name="TestImg"
                   Source="/MyTests;component/Resources/Approval.png"
                   Margin="7">
            </Image>
            <Label Name="TestName"
                   Content="Название теста"
                   FontSize="25">
            </Label>
        </StackPanel>
        <StackPanel Orientation="Horizontal"
                    HorizontalAlignment="Right">
            <Label Content="by"
                   FontSize="25">
            </Label>
            <Image Name="AuthorImg"
                   Source="/MyTests;component/Resources/StandartImage.png"
                   Margin="7">
            </Image>
            <Label Name="AuthorName"
                   Content="Автор"
                   FontSize="25">
            </Label>
        </StackPanel>
        <ListBox Name="TestsListBox"
                 Background="{StaticResource color1}"
                 BorderBrush="{Binding TestsListBox}" 
                 Grid.Row="1">
            <ScrollViewer VerticalScrollBarVisibility="Visible"/>
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Border Width="{Binding Path=ActualWidth, ElementName=TestsListBox}"
                            Height="50"
                            CornerRadius="10"
                            Background="{StaticResource color2}"
                            MouseDown="TestsListBox_Selected">
                        <StackPanel>
                            <Label Content="{Binding Content}"/>
                            <TextBox Name="Testing"
                                     Text="Ответ:"/>
                        </StackPanel>
                    </Border>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</Page>