question

Hi LukaCiglar,

It's not impossible, but it's difficult to do it completely ,because this cannot be handled across page boundaries.

 <Window x:Class="WpfApp1.MainWindow"
         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"
         xmlns:local="clr-namespace:WpfApp1"
         mc:Ignorable="d"
         Title="MainWindow" Height="450" Width="800">
    
     <Grid >
         <FlowDocumentScrollViewer >
             <FlowDocumentScrollViewer.Document>
                 <FlowDocument >
                     <FlowDocument.Resources>
                         <Style TargetType="TableCell">
                             <Setter Property="BorderBrush" Value="Transparent"/>
                             <Setter Property="BorderThickness" Value="1,1,1,1" />
                         </Style>
                     </FlowDocument.Resources>
    
                     <Table CellSpacing="0">
                         <Table.Columns>
                             <TableColumn Width="100"/>
                             <TableColumn Width="100" />
                             <TableColumn Width="100"/>
                         </Table.Columns>
    
                         <TableRowGroup >
                             <TableRow >
                                 <TableCell RowSpan="2" BorderThickness="0" >
    
                                     <BlockUIContainer>
                                         <Canvas HorizontalAlignment="Left" VerticalAlignment="Stretch" >
                                             <Border Background="Transparent"
                                                     BorderBrush="Red"
                                                     BorderThickness="1"
                                                     CornerRadius="5,0,0,5"
                                                     Loaded="Border_Loaded"  />
                                         </Canvas>
                                     </BlockUIContainer>
                                     <Paragraph >
                                         <Run >ABCDEFGHIJKLMNOPQRSTUVWXYZ</Run>
                                     </Paragraph>
                                 </TableCell>
    
                                 <TableCell ColumnSpan="2" BorderThickness="0" >
                                     <local:BorderEx Background="LightYellow"
                                                     BorderBrush="Green"  
                                                     BorderThickness="2"
                                                     CornerRadius="10"/>
                                     <Paragraph Margin="5">
                                         <Run>ABCDEFGHIJKLMNOPQRSTUVWXYZ</Run>
                                     </Paragraph>
                                 </TableCell>
    
                             </TableRow>
    
                             <TableRow>
                                 <TableCell />
                                 <TableCell BorderBrush="Black" BorderThickness="1"/>
                             </TableRow>
                         </TableRowGroup>
                     </Table>
    
                 </FlowDocument>
             </FlowDocumentScrollViewer.Document>
         </FlowDocumentScrollViewer>
     </Grid>
 </Window>

---

 namespace WpfApp1
 {
     using System;
     using System.Collections;
     using System.Windows;
     using System.Windows.Controls;
     using System.Windows.Data;
     using System.Windows.Documents;
     using System.Windows.Media;
    
     public partial class MainWindow : Window
     {
         public MainWindow()
         {
             InitializeComponent();
         }
    
         private void Border_Loaded(object sender, RoutedEventArgs e)
         {
             BorderEx.Border_Loaded(sender, e);
         }
     }
    
     class BorderEx : BlockUIContainer
     {
         public static void Border_Loaded(object sender, RoutedEventArgs e)
         {
             Border border = (Border)sender;
             DependencyObject da = border;
             DependencyObject db = null;
             while (da != null)
             {
                 if (da.GetType().Name == "RowVisual")
                 {
                     var cv = db as System.Windows.Media.ContainerVisual;
                     if (cv != null)
                     {
                         border.Width = cv.DescendantBounds.Width;
                         border.Height = cv.DescendantBounds.Height;
                     }
                     break;
                 }
                 db = da;
                 da = VisualTreeHelper.GetParent(da);
             }
         }
    
         public BorderEx()
         {
             this.Loaded += BorderEx_Loaded;
         }
    
         private void BorderEx_Loaded(object sender, RoutedEventArgs e)
         {
             Border border = new Border();
             border.SetBinding(Border.BorderBrushProperty, new Binding() { Path = new PropertyPath(BorderEx.BorderBrushProperty), Source = this });
             border.SetBinding(Border.BorderThicknessProperty, new Binding() { Path = new PropertyPath(BorderEx.BorderThicknessProperty), Source = this });
             border.SetBinding(Border.CornerRadiusProperty, new Binding() { Path = new PropertyPath(BorderEx.CornerRadiusProperty), Source = this });
             border.SetBinding(Border.BackgroundProperty, new Binding() { Path = new PropertyPath(BorderEx.BackgroundProperty), Source = this });
             border.Loaded += Border_Loaded;
    
             Canvas cv = new Canvas();
             cv.Width = 0;
             cv.Height = 0;
             cv.HorizontalAlignment = HorizontalAlignment.Left;
             cv.VerticalAlignment = VerticalAlignment.Top;
             cv.Children.Add(border);
             this.Child = cv;
         }
    
         public CornerRadius CornerRadius
         {
             get { return (CornerRadius)GetValue(CornerRadiusProperty); }
             set { SetValue(CornerRadiusProperty, value); }
         }
         public static readonly DependencyProperty CornerRadiusProperty = DependencyProperty.Register("CornerRadius", typeof(CornerRadius), typeof(BorderEx), new PropertyMetadata(default(CornerRadius)));
    
         public new Thickness BorderThickness
         {
             get { return (Thickness)GetValue(BorderThicknessProperty); }
             set { SetValue(BorderThicknessProperty, value); }
         }
         public new static readonly DependencyProperty BorderThicknessProperty = DependencyProperty.Register("BorderThickness", typeof(Thickness), typeof(BorderEx), new PropertyMetadata(default(Thickness)));
     }
 }