Show Tooltip when text is being trimmed

Answer 1

I found the simplest solution to extend TextBlock and compare text lengths to determine whether to show tooltip, i.e.,

public class ToolTipTextBlock : TextBlock
   {
      protected override void OnToolTipOpening(ToolTipEventArgs e)
      {
         if (TextTrimming != TextTrimming.None)
         {
           e.Handled = !IsTextTrimmed();
         }
      }

      private bool IsTextTrimmed()
      {
         var typeface = new Typeface(FontFamily, FontStyle, FontWeight, FontStretch);
         var formattedText = new FormattedText(Text, CultureInfo.CurrentCulture, FlowDirection, typeface, FontSize, Foreground);
         return formattedText.Width > ActualWidth;
      }
   }

Then simply use this custom text block in xaml as follows: