From 8d6f1628b25aabbb162c533895d33147c98cb8ce Mon Sep 17 00:00:00 2001
From: BDisp <bd.bdisp@gmail.com>
Date: Wed, 12 Nov 2025 21:55:05 +0000
Subject: [PATCH] Fix IsValidLocation for wide graphemes

---
 Terminal.Gui/Drivers/OutputBufferImpl.cs      |  7 +--
 .../Drivers/DriverTests.cs                    | 46 ++++++++++++++++++-
 2 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/Terminal.Gui/Drivers/OutputBufferImpl.cs b/Terminal.Gui/Drivers/OutputBufferImpl.cs
index 02237d23c..ee573789b 100644
--- a/Terminal.Gui/Drivers/OutputBufferImpl.cs
+++ b/Terminal.Gui/Drivers/OutputBufferImpl.cs
@@ -289,12 +289,9 @@ public class OutputBufferImpl : IOutputBuffer
     /// </returns>
     public bool IsValidLocation (string text, int col, int row)
     {
-        if (text.GetColumns () < 2)
-        {
-            return col >= 0 && row >= 0 && col < Cols && row < Rows && Clip!.Contains (col, row);
-        }
+        int textWidth = text.GetColumns ();
 
-        return Clip!.Contains (col, row) || Clip!.Contains (col + 1, row);
+        return col >= 0 && row >= 0 && col + textWidth <= Cols && row < Rows && Clip!.Contains (col, row);
     }
 
     /// <inheritdoc/>
diff --git a/Tests/UnitTestsParallelizable/Drivers/DriverTests.cs b/Tests/UnitTestsParallelizable/Drivers/DriverTests.cs
index 9f87d80d0..ee4755507 100644
--- a/Tests/UnitTestsParallelizable/Drivers/DriverTests.cs
+++ b/Tests/UnitTestsParallelizable/Drivers/DriverTests.cs
@@ -1,6 +1,50 @@
 using UnitTests;
+using Xunit.Abstractions;
 
 namespace UnitTests_Parallelizable.DriverTests;
 
 public class DriverTests : FakeDriverBase
-{ }
+{
+    [Theory]
+    [InlineData (null, true)]
+    [InlineData ("", true)]
+    [InlineData ("a", true)]
+    [InlineData ("👩‍❤️‍💋‍👨", false)]
+    public void IsValidLocation (string text, bool positive)
+    {
+        IDriver driver = CreateFakeDriver ();
+        driver.SetScreenSize (10, 10);
+
+        // positive
+        Assert.True (driver.IsValidLocation (text, 0, 0));
+        Assert.True (driver.IsValidLocation (text, 1, 1));
+        Assert.Equal (positive, driver.IsValidLocation (text, driver.Cols - 1, driver.Rows - 1));
+
+        // negative
+        Assert.False (driver.IsValidLocation (text, -1, 0));
+        Assert.False (driver.IsValidLocation (text, 0, -1));
+        Assert.False (driver.IsValidLocation (text, -1, -1));
+        Assert.False (driver.IsValidLocation (text, driver.Cols, driver.Rows - 1));
+        Assert.False (driver.IsValidLocation (text, driver.Cols, driver.Rows - 1));
+        Assert.False (driver.IsValidLocation (text, driver.Cols, driver.Rows));
+
+        // Define a clip rectangle
+        driver.Clip = new (new Rectangle (5, 5, 5, 5));
+
+        // positive
+        Assert.True (driver.IsValidLocation (text, 5, 5));
+        Assert.Equal (positive, driver.IsValidLocation (text, 9, 9));
+
+        // negative
+        Assert.False (driver.IsValidLocation (text, 4, 5));
+        Assert.False (driver.IsValidLocation (text, 5, 4));
+        Assert.False (driver.IsValidLocation (text, 10, 9));
+        Assert.False (driver.IsValidLocation (text, 9, 10));
+        Assert.False (driver.IsValidLocation (text, -1, 0));
+        Assert.False (driver.IsValidLocation (text, 0, -1));
+        Assert.False (driver.IsValidLocation (text, -1, -1));
+        Assert.False (driver.IsValidLocation (text, driver.Cols, driver.Rows - 1));
+        Assert.False (driver.IsValidLocation (text, driver.Cols, driver.Rows - 1));
+        Assert.False (driver.IsValidLocation (text, driver.Cols, driver.Rows));
+    }
+}