View difference between Paste ID: Qyqb2UZx and 7Xw0BsrN

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Documents;
 using System.Windows.Media;
 
 namespace SO3WPF
 {
     public class HighlightTextBlock : ContentControl
     {
 
         public string Text
         {
             get { return (string)GetValue(TextProperty); }
             set { SetValue(TextProperty, value); }
         }
 
         public static readonly DependencyProperty TextProperty =
             DependencyProperty.Register("Text", typeof(string), typeof(HighlightTextBlock), new UIPropertyMetadata("", SetContentStatic));
 
         private static void SetContentStatic(DependencyObject d, DependencyPropertyChangedEventArgs e)
         {
             var control = d as HighlightTextBlock;
             control.SetContent();
         }
 
         public string HighlightText
         {
             get { return (string)GetValue(HighlightTextProperty); }
             set { SetValue(HighlightTextProperty, value); }
         }
 
         public static readonly DependencyProperty HighlightTextProperty =
             DependencyProperty.Register("HighlightText", typeof(string), typeof(HighlightTextBlock), new UIPropertyMetadata("", SetContentStatic));
 
         public Brush HighlightBrush
         {
             get { return (Brush)GetValue(ColorProperty); }
             set { SetValue(ColorProperty, value); }
         }
 
         public static readonly DependencyProperty ColorProperty =
             DependencyProperty.Register("HighlightBrush", typeof(Brush), typeof(HighlightTextBlock), new UIPropertyMetadata(Brushes.Orange));
 
         private TextBlock TextContent = new TextBlock();
 
         public HighlightTextBlock()
         {
             Content = TextContent;
             SetContent();
         }
 
         int updateId = 0;
         private void SetContentOld()
         {
             var currentUpdateId = ++updateId;
             var text = Text;
             var highlightText = HighlightText;
             var parts = GetCombined(text, highlightText);//await Task.Run(() => GetCombined(text, highlightText));
             if (currentUpdateId != updateId)
                 return;
             ApplyParts(parts);
         }
 
         Task currentWaitTask = null;
         private async void SetContent45()
         {
             var waitTask = Task.Delay(TimeSpan.FromSeconds(0.1));
             currentWaitTask = waitTask;
             await waitTask;
             if (currentWaitTask != waitTask)
                 return;
 
             var text = Text;
             var highlightText = HighlightText;
             var parts = await Task.Run(() => GetCombined(text, highlightText));
             if (currentWaitTask != waitTask)
                 return;
 
             currentWaitTask = null;
             ApplyParts(parts);
         }
 
         private void SetContent()
         {
             var mainTS = TaskScheduler.FromCurrentSynchronizationContext();
             var waitTask = Task.Delay(TimeSpan.FromSeconds(0.1));
             currentWaitTask = waitTask;
             waitTask.ContinueWith(t =>
                 {
                     if (currentWaitTask != waitTask)
                         return;
                     var text = Text;
                     var highlightText = HighlightText;
 
-                    Task.Run(() => GetCombined(text, highlightText)).ContinueWith(ctask =>
+                    var parts = GetCombined(text, highlightText);
-                    {
+                    currentWaitTask = null;
-                        var parts = ctask.Result;
+                    ApplyParts(parts);
-                        if (currentWaitTask != waitTask)
+
-                            return;
+
-                        currentWaitTask = null;
+
-                        ApplyParts(parts);
+
-                    }, mainTS);
+
             var highlightBrush = HighlightBrush;
             System.Collections.IList existingInlines = TextContent.Inlines;
             var existingCount = existingInlines.Count;
             List<Inline> inlinesToAdd = null;
             var max = Math.Max(existingCount, parts.Count);
             for (int i = 0; i < max; i++)
             {
                 var text = i < parts.Count ? parts[i] : null;
                 if (i < existingCount)
                 {
                     ((Run)existingInlines[i]).Text = text;
                 }
                 else // add new inline
                 {
                     var inline = new Run(text);
                     if (i % 2 != 0) // highlight
                         inline.Background = highlightBrush;
                     if (inlinesToAdd == null)
                         inlinesToAdd = new List<Inline>(parts.Count);
                     inlinesToAdd.Add(inline);
                 }
             }
             if (inlinesToAdd != null)
                 TextContent.Inlines.AddRange(inlinesToAdd);
         }
 
         private List<string> GetCombined(string text, string highlightText)
         {
             var list = new List<string>();
             if (text == null)
                 return list;
             if (highlightText == null)
             {
                 list.Add(text);
                 return list;
             }
 
             var parts = text.Split(new[] { highlightText }, StringSplitOptions.None);
             bool first = true;
             foreach (var part in parts)
             {
                 if (!first)
                     list.Add(highlightText);
                 list.Add(part);
                 first = false;
             }
             return list;
         }
     }
 }