From a429159c3c32bca2b278763b02ebaede05148ab6 Mon Sep 17 00:00:00 2001
From: Deadpikle <mbabienco@southern.edu>
Date: Wed, 11 Mar 2020 17:20:52 -0400
Subject: [PATCH 1/2] Add SelectedText to TextBox

---
 src/Avalonia.Controls/TextBox.cs | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/Avalonia.Controls/TextBox.cs b/src/Avalonia.Controls/TextBox.cs
index a438d7380b..943a73b427 100644
--- a/src/Avalonia.Controls/TextBox.cs
+++ b/src/Avalonia.Controls/TextBox.cs
@@ -275,6 +275,22 @@ namespace Avalonia.Controls
             }
         }
 
+        public string SelectedText
+        {
+            get { return GetSelection(); }
+            set
+            {
+                if (value == null)
+                {
+                    return;
+                }
+
+                _undoRedoHelper.Snapshot();
+                HandleTextInput(value);
+                _undoRedoHelper.Snapshot();
+            }
+        }
+
         /// <summary>
         /// Gets or sets the horizontal alignment of the content within the control.
         /// </summary>

From 47f487e768443813ea5e892bfa2e3ad8a6f0609a Mon Sep 17 00:00:00 2001
From: Deadpikle <mbabienco@southern.edu>
Date: Wed, 11 Mar 2020 17:27:06 -0400
Subject: [PATCH 2/2] Add SelectedText unit tests

---
 .../TextBoxTests.cs                           | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/tests/Avalonia.Controls.UnitTests/TextBoxTests.cs b/tests/Avalonia.Controls.UnitTests/TextBoxTests.cs
index 225eca17b2..14251454ea 100644
--- a/tests/Avalonia.Controls.UnitTests/TextBoxTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/TextBoxTests.cs
@@ -385,6 +385,49 @@ namespace Avalonia.Controls.UnitTests
                 Assert.True(target.SelectionEnd <= "123".Length);
             }
         }
+
+        [Fact]
+        public void SelectedText_Changes_OnSelectionChange()
+        {
+            using (UnitTestApplication.Start(Services))
+            {
+                var target = new TextBox
+                {
+                    Template = CreateTemplate(),
+                    Text = "0123456789"
+                };
+
+                Assert.True(target.SelectedText == "");
+
+                target.SelectionStart = 2;
+                target.SelectionEnd = 4;
+
+                Assert.True(target.SelectedText == "23");
+            }
+        }
+
+        [Fact]
+        public void SelectedText_EditsText()
+        {
+            using (UnitTestApplication.Start(Services))
+            {
+                var target = new TextBox
+                {
+                    Template = CreateTemplate(),
+                    Text = "0123"
+                };
+
+                target.SelectedText = "AA";
+                Assert.True(target.Text == "AA0123");
+
+                target.SelectionStart = 1;
+                target.SelectionEnd = 3;
+                target.SelectedText = "BB";
+
+                Assert.True(target.Text == "ABB123");
+            }
+        }
+
         [Fact]
         public void CoerceCaretIndex_Doesnt_Cause_Exception_with_malformed_line_ending()
         {