Use Run the mark underlink TextDecorations : TextBlock « Windows Presentation Foundation « VB.Net Tutorial

1. VB.Net Tutorial
2. Windows Presentation Foundation
3. TextBlock

<Window x:Class="ClassicControls.PopupTest"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="PopupTest" Height="300" Width="300">
    <Grid Margin="10">
      <TextBlock TextWrapping="Wrap">text 
         <Run TextDecorations="Underline" MouseEnter="run_MouseEnter">link</Run>
      </TextBlock>
      <Popup Name="popLink" StaysOpen="False" Placement="Mouse" MaxWidth="200" PopupAnimation="Slide" AllowsTransparency = "True">
        <Border BorderBrush="Beige" BorderThickness="2" Background="White">
          <TextBlock Margin="10"  TextWrapping="Wrap" >
            check out
            <Hyperlink NavigateUri="http://java2s.com" Click="lnk_Click">java2s.com</Hyperlink>
          </TextBlock>
        </Border>
      </Popup>
    </Grid>
</Window>
//File:Window.xaml.vb

Imports System
Imports System.Collections.Generic
Imports System.Text
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Data
Imports System.Windows.Documents
Imports System.Windows.Input
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
Imports System.Windows.Shapes
Imports System.Diagnostics

Namespace ClassicControls
  Public Partial Class PopupTest
    Inherits System.Windows.Window

    Public Sub New()
      InitializeComponent()
    End Sub

    Private Sub run_MouseEnter(sender As Object, e As MouseEventArgs)
      popLink.IsOpen = True
    End Sub
    Private Sub lnk_Click(sender As Object, e As RoutedEventArgs)
      Process.Start(DirectCast(sender, Hyperlink).NavigateUri.ToString())
    End Sub
  End Class
End Namespace

16.1.TextBlock
	16.1.1.	Simple TextBlock
	16.1.2.	Simple content
	16.1.3.	LineBreak inside a TextBlock
	16.1.4.	Semi-Transparent TextBlock
	16.1.5.	TextBlock.Foreground and ImageBrush
	16.1.6.	Multi-span for TextBlock
	16.1.7.	Setting text decorations
	16.1.8.	Set pen for TextDecorations
	16.1.9.	TextTrimming for TextBlock
	16.1.10.	Layout TextBlock in UniformGrid
	16.1.11.	Text as content
	16.1.12.	Text with mixed content
	16.1.13.	Whitespace as content and as attribute
	16.1.14.	Preserving whitespace in mixed content
	16.1.15.	Nested TextBlock
	16.1.16.	Enabling hyphenation
	16.1.17.	Positioning a hosted Button element with BaselineAlignment along with text
	16.1.18.	Using RenderTransform
	16.1.19.	This is rotating text
	16.1.20.	Handling overflow
	16.1.21.	Use Run the mark underlink TextDecorations
	16.1.22.	Simple underline decoration
	16.1.23.	Effects of the enumerated values of TextWrapping.
	16.1.24.	Programmatically change the way in which TextBlock is trimmed when it exceeds the outer boundaries of its containing box.