Show ellipsis when MaxLines are reached

samples/Sandbox/MainWindow.axaml

@@ -1,5 +1,4 @@
 <Window xmlns="https://github.com/avaloniaui"
         xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'
         x:Class="Sandbox.MainWindow">
-  <TextBlock TextDecorations="Underline" Text="Underline "/>
 </Window>

src/Avalonia.Base/Media/TextFormatting/TextLayout.cs

@@ -479,6 +479,11 @@ namespace Avalonia.Media.TextFormatting
                 //Fulfill max lines constraint
                 if (MaxLines > 0 && textLines.Count >= MaxLines)
                 {
+                    if(textLine.TextLineBreak is TextLineBreak lineBreak && lineBreak.RemainingRuns != null)
+                    {
+                        textLines[textLines.Count - 1] = textLine.Collapse(GetCollapsingProperties(width));
+                    }
+
                     break;
                 }
             }