UWP recherche d'un mot précis dans une chaine TextBlock

Question

Bonjour, j'ai un Textblock qui contient un certain nombre de mots et un code qui recherche un mot précis ici par exemple "that".

Je souhaiterais que si le mot est trouvé il se mette en rouge.

 <StackPanel Margin="20">
            <TextBlock FontFamily="Verdana"
                       Name="TB1"
                       FontSize="28"
           LineStackingStrategy="MaxHeight" 
           LineHeight="10" 
           Width="500" 
           TextWrapping="Wrap" >
    Use the <Run FontSize="30">LineStackingStrategy</Run> property to determine how a line box is
    created for each line. A value of <Run FontSize="20">MaxHeight</Run> specifies that the stack
    height is the smallest value that contains all the inline elements on that line when those
    elements are properly aligned. A value of <Run FontSize="20">BlockLineHeight</Run> specifies
    that the stack height is determined by the block element LineHeight property value.
            </TextBlock>
            <StackPanel Margin="0,20,0,0" HorizontalAlignment="Center">
                <Line Stroke="Green"  X2="500" />
            </StackPanel>

        </StackPanel>

  public MainPage()
        {
            this.InitializeComponent();
            string zonetext = TB1.Text;
            string mot = "that";
            if (zonetext.Contains(mot)==true)
            {
               // mot.Foreground=Brushes.Red;
            }
        }

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JF Collombet ® CreateSpecificCulture