Can I have multiple colors in a single TextBlock in WPF?

I think what you mean is like this( not styling for textblock):

<TextBlock  FontSize="25" >
   <Run Text="Detected [" Foreground="Red"/><Run Text="gesture" Foreground="Gray"/>
   <Run Text="] with an accuracy of [" Foreground="Yellow"/><Run Text="accuracy]" Foreground="Green"/>
</TextBlock>

Note: every enter(or new line) between Run tag make have space between them.

I know this post is old, but have you tried this?? You can actually add multi colored text, this way in a TextBlock..

Xaml: <TextBlock x:Name="txt_Txt"/>


foreach (var itm5 in "! Hello World !; %Hello World%".Split(';'))
{
       if (txt_Txt.Inlines.Count() > 0)
           txt_Txt.Inlines.Add(new Run("\r\n"));
       foreach (var letter in itm5)
       {
            if (char.IsSymbol(letter))
               txt_Txt.Inlines.Add(new Run(letter.ToString()) { Foreground = Brushes.Red });
            else
                txt_Txt.Inlines.Add(new Run(letter.ToString()) { Foreground = Brushes.Black });
        }
}

See if this helps:

 <TextBlock>
      Detected
      <TextBlock Text="{Binding Gesture}" Foreground="Red" />
      with an accuracy of
      <TextBlock Text="{Binding Accuracy}" />
 </TextBlock>