Fixes #4440. TextView with ReadOnly as true, MoveRight doesn't select text up to the end of the line (#4441)

* Fixes #4440. TextView with ReadOnly as true, MoveRight doesn't select text up to the end of the line

* Each character must return at least one column, with the exception of Tab.

* Add unit test for the LeftColumn

Terminal.Gui/Views/TextInput/TextModel.cs

@@ -616,7 +616,8 @@ internal class TextModel
         for (; i < tCount; i++)
         {
             string text = t [i];
-            size += text.GetColumns (false);
+            int colWidth = text.GetColumns (false);
+            size += colWidth;
             len += text.Length;
 
             if (text == "\t")
@@ -624,6 +625,10 @@ internal class TextModel
                 size += tabWidth + 1;
                 len += tabWidth - 1;
             }
+            else if (colWidth == -1)
+            {
+                size += 2; // -1+2=1
+            }
 
             if (checkNextRune && i == tCount - 1 && t.Count > tCount && IsWideText (t [i + 1], tabWidth, out int s, out int l))
             {

Terminal.Gui/Views/TextInput/TextView.cs

@@ -3654,7 +3654,7 @@ public class TextView : View, IDesignable
     {
         List<Cell> currentLine = GetCurrentLine ();
 
-        if ((ReadOnly ? CurrentColumn + 1 : CurrentColumn) < currentLine.Count)
+        if (CurrentColumn < currentLine.Count)
         {
             CurrentColumn++;
         }

Tests/UnitTestsParallelizable/Views/TextViewTests.cs

@@ -2405,5 +2405,44 @@ public class TextViewTests
         Assert.Equal (expectedText, tv.SelectedText);
     }
 
+    [Fact]
+    public void ReadOnly_True_Move_Right_Moves_Until_The_End_Of_Text_More_One_Column ()
+    {
+        TextView tv = CreateTextView ();
+        tv.Text = "Hi";
+        tv.ReadOnly = true;
+
+        Assert.Equal (0, tv.CurrentColumn);
+
+        Assert.True (tv.NewKeyDownEvent (Key.CursorRight.WithShift));
+        Assert.Equal (1, tv.CurrentColumn);
+        Assert.Equal ("H", tv.SelectedText);
+
+        Assert.True (tv.NewKeyDownEvent (Key.CursorRight.WithShift));
+        Assert.Equal (2, tv.CurrentColumn);
+        Assert.Equal ("Hi", tv.SelectedText);
+    }
+
+    [Fact]
+    public void LeftColumn_Treat_Negative_Width_As_One_Column ()
+    {
+        TextView tv = new () { Width = 2, Height = 1, Text = "\u001B[" };
+
+        Assert.Equal (0, tv.LeftColumn);
+        Assert.Equal (new (0, 0), tv.CursorPosition);
+
+        Assert.True (tv.NewKeyDownEvent (Key.CursorRight));
+        Assert.Equal (0, tv.LeftColumn);
+        Assert.Equal (new (1, 0), tv.CursorPosition);
+
+        Assert.True (tv.NewKeyDownEvent (Key.CursorRight));
+        Assert.Equal (1, tv.LeftColumn);
+        Assert.Equal (new (2, 0), tv.CursorPosition);
+
+        Assert.False (tv.NewKeyDownEvent (Key.CursorRight));
+        Assert.Equal (1, tv.LeftColumn);
+        Assert.Equal (new (2, 0), tv.CursorPosition);
+    }
+
     private TextView CreateTextView () { return new () { Width = 30, Height = 10 }; }
 }