diff --git a/src/DiagramEditor/ClassDiagram/Editors/BorderedTextBox.cs b/src/DiagramEditor/ClassDiagram/Editors/BorderedTextBox.cs
index 5849733..79112e3 100644
--- a/src/DiagramEditor/ClassDiagram/Editors/BorderedTextBox.cs
+++ b/src/DiagramEditor/ClassDiagram/Editors/BorderedTextBox.cs
@@ -23,35 +23,6 @@ namespace NClass.DiagramEditor.ClassDiagram.Editors
 {
     public class BorderedTextBox : UserControl
     {
-        private class TabTextBox : TextBox
-        {
-            [DefaultValue(true)]
-            public bool AllowSelectAll { get; set; }
-
-            protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
-            {
-                if (keyData == Keys.Enter && AcceptsReturn)
-                {
-                    OnKeyDown(new KeyEventArgs(keyData));
-                    return true;
-                }
-                else if (keyData == Keys.Tab && AcceptsTab)
-                {
-                    OnKeyDown(new KeyEventArgs(keyData));
-                    return true;
-                }
-                else if (keyData == (Keys.A | Keys.Control) && AllowSelectAll)
-                {
-                    SelectAll();
-                    return true;
-                }
-                else
-                {
-                    return base.ProcessCmdKey(ref msg, keyData);
-                }
-            }
-        }
-
         readonly TabTextBox textBox = new TabTextBox();
         readonly Panel panel = new Panel();
 
diff --git a/src/DiagramEditor/ClassDiagram/Editors/TabTextBox.cs b/src/DiagramEditor/ClassDiagram/Editors/TabTextBox.cs
new file mode 100644
index 0000000..645de85
--- /dev/null
+++ b/src/DiagramEditor/ClassDiagram/Editors/TabTextBox.cs
@@ -0,0 +1,49 @@
+// NClass - Free class diagram editor
+// Copyright (C) 2023 Georgi Baychev
+// 
+// This program is free software; you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free Software
+// Foundation; either version 3 of the License, or (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+// 
+// You should have received a copy of the GNU General Public License along with
+// this program; if not, write to the Free Software Foundation, Inc.,
+// 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+using System.ComponentModel;
+using System.Windows.Forms;
+
+namespace NClass.DiagramEditor.ClassDiagram.Editors
+{
+    public class TabTextBox : TextBox
+    {
+        [DefaultValue(true)]
+        public bool AllowSelectAll { get; set; }
+
+        protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
+        {
+            if (keyData == Keys.Enter && AcceptsReturn)
+            {
+                OnKeyDown(new KeyEventArgs(keyData));
+                return true;
+            }
+            else if (keyData == Keys.Tab && AcceptsTab)
+            {
+                OnKeyDown(new KeyEventArgs(keyData));
+                return true;
+            }
+            else if (keyData == (Keys.A | Keys.Control) && AllowSelectAll)
+            {
+                SelectAll();
+                return true;
+            }
+            else
+            {
+                return base.ProcessCmdKey(ref msg, keyData);
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/DiagramEditor/DiagramEditor.csproj b/src/DiagramEditor/DiagramEditor.csproj
index ba085c8..95440d3 100644
--- a/src/DiagramEditor/DiagramEditor.csproj
+++ b/src/DiagramEditor/DiagramEditor.csproj
@@ -69,6 +69,9 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="AbsoluteMouseEventArgs.cs" />
+    <Compile Include="ClassDiagram\Editors\TabTextBox.cs">
+      <SubType>Component</SubType>
+    </Compile>
     <Compile Include="Commands\AddConnectionCommand.cs" />
     <Compile Include="Commands\AddDelegateParameterCommand.cs" />
     <Compile Include="Commands\AddEnumMemberCommand.cs" />