DeleteWindow.xaml

<Window x:Class="Backupr.DeleteWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Delete" Height="229" Width="504" WindowStyle="SingleBorderWindow" ResizeMode="NoResize">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <StackPanel Margin="5">
            <GroupBox Header="Please select, what you want to delete">
                <StackPanel Margin="5">
                    <CheckBox Content="Photosets" IsChecked="{Binding DeletePhotosets, Mode=TwoWay}"/>
                    <CheckBox Content="Photos" IsChecked="{Binding DeletePhotos, Mode=TwoWay}"/>
                </StackPanel>
            </GroupBox>

        </StackPanel>

        
        <GroupBox Header="Confirmation" Grid.Row="1" >
            <StackPanel Margin="5">
                <TextBlock FontWeight="Bold" Foreground="Red" Text="This action CANNOT be UNDONE, all content will be lost" TextWrapping="Wrap" />
                <CheckBox Content="I agree" x:Name="agreement"/>
            </StackPanel>
        </GroupBox>
        <StackPanel Grid.Row="2" Orientation="Horizontal" HorizontalAlignment="Right">
            <StackPanel.Resources>
                <Style TargetType="Button">
                    <Setter Property="Padding" Value="5"/>
                    <Setter Property="Margin" Value="5"/>
                    <Setter Property="MinWidth" Value="120"/>
                </Style>
            </StackPanel.Resources>
            <Button Content="Delete" IsDefault="False" IsEnabled="{Binding ElementName=agreement, Path=IsChecked}" Click="Button_Click"/>
            <Button Content="Cancel" IsCancel="True" Click="Button_Click_1"/>
        </StackPanel>
    </Grid>
</Window>