diff --git a/DarkUI/Docking/DarkDockPanel.cs b/DarkUI/Docking/DarkDockPanel.cs
index 92c74e4..2eaa833 100644
--- a/DarkUI/Docking/DarkDockPanel.cs
+++ b/DarkUI/Docking/DarkDockPanel.cs
@@ -111,7 +111,7 @@ namespace DarkUI.Docking
         public void AddContent(DarkDockContent dockContent, DarkDockGroup dockGroup)
         {
             if (_contents.Contains(dockContent))
-                return;
+                RemoveContent(dockContent);
 
             if (dockGroup != null && dockContent.DockArea != dockGroup.DockArea)
                 throw new Exception($"Attempting to add '{dockContent.DockArea}' content to '{dockGroup.DockArea}' group.");
diff --git a/Example/Forms/Docking/DockProperties.Designer.cs b/Example/Forms/Docking/DockProperties.Designer.cs
index 6bd766a..5fe6477 100644
--- a/Example/Forms/Docking/DockProperties.Designer.cs
+++ b/Example/Forms/Docking/DockProperties.Designer.cs
@@ -30,22 +30,134 @@ namespace Example
         /// </summary>
         private void InitializeComponent()
         {
+            this.pnlMain = new System.Windows.Forms.Panel();
+            this.panel1 = new System.Windows.Forms.Panel();
+            this.darkCheckBox1 = new DarkUI.Controls.DarkCheckBox();
+            this.darkCheckBox2 = new DarkUI.Controls.DarkCheckBox();
+            this.darkCheckBox3 = new DarkUI.Controls.DarkCheckBox();
+            this.darkRadioButton1 = new DarkUI.Controls.DarkRadioButton();
+            this.darkRadioButton2 = new DarkUI.Controls.DarkRadioButton();
+            this.darkRadioButton3 = new DarkUI.Controls.DarkRadioButton();
+            this.pnlMain.SuspendLayout();
+            this.panel1.SuspendLayout();
             this.SuspendLayout();
             // 
+            // pnlMain
+            // 
+            this.pnlMain.Controls.Add(this.panel1);
+            this.pnlMain.Dock = System.Windows.Forms.DockStyle.Fill;
+            this.pnlMain.Location = new System.Drawing.Point(0, 25);
+            this.pnlMain.Name = "pnlMain";
+            this.pnlMain.Padding = new System.Windows.Forms.Padding(10);
+            this.pnlMain.Size = new System.Drawing.Size(280, 425);
+            this.pnlMain.TabIndex = 0;
+            // 
+            // panel1
+            // 
+            this.panel1.AutoSize = true;
+            this.panel1.Controls.Add(this.darkRadioButton3);
+            this.panel1.Controls.Add(this.darkRadioButton2);
+            this.panel1.Controls.Add(this.darkRadioButton1);
+            this.panel1.Controls.Add(this.darkCheckBox3);
+            this.panel1.Controls.Add(this.darkCheckBox2);
+            this.panel1.Controls.Add(this.darkCheckBox1);
+            this.panel1.Dock = System.Windows.Forms.DockStyle.Top;
+            this.panel1.Location = new System.Drawing.Point(10, 10);
+            this.panel1.Name = "panel1";
+            this.panel1.Padding = new System.Windows.Forms.Padding(0, 0, 0, 5);
+            this.panel1.Size = new System.Drawing.Size(260, 152);
+            this.panel1.TabIndex = 0;
+            // 
+            // darkCheckBox1
+            // 
+            this.darkCheckBox1.AutoSize = true;
+            this.darkCheckBox1.Location = new System.Drawing.Point(0, 0);
+            this.darkCheckBox1.Name = "darkCheckBox1";
+            this.darkCheckBox1.Size = new System.Drawing.Size(78, 19);
+            this.darkCheckBox1.TabIndex = 1;
+            this.darkCheckBox1.Text = "Checkbox";
+            // 
+            // darkCheckBox2
+            // 
+            this.darkCheckBox2.AutoSize = true;
+            this.darkCheckBox2.Enabled = false;
+            this.darkCheckBox2.Location = new System.Drawing.Point(0, 25);
+            this.darkCheckBox2.Name = "darkCheckBox2";
+            this.darkCheckBox2.Size = new System.Drawing.Size(124, 19);
+            this.darkCheckBox2.TabIndex = 2;
+            this.darkCheckBox2.Text = "Disabled checkbox";
+            // 
+            // darkCheckBox3
+            // 
+            this.darkCheckBox3.AutoSize = true;
+            this.darkCheckBox3.Checked = true;
+            this.darkCheckBox3.CheckState = System.Windows.Forms.CheckState.Checked;
+            this.darkCheckBox3.Enabled = false;
+            this.darkCheckBox3.Location = new System.Drawing.Point(0, 50);
+            this.darkCheckBox3.Name = "darkCheckBox3";
+            this.darkCheckBox3.Size = new System.Drawing.Size(171, 19);
+            this.darkCheckBox3.TabIndex = 3;
+            this.darkCheckBox3.Text = "Disabled checked checkbox";
+            // 
+            // darkRadioButton1
+            // 
+            this.darkRadioButton1.AutoSize = true;
+            this.darkRadioButton1.Location = new System.Drawing.Point(0, 75);
+            this.darkRadioButton1.Name = "darkRadioButton1";
+            this.darkRadioButton1.Size = new System.Drawing.Size(91, 19);
+            this.darkRadioButton1.TabIndex = 4;
+            this.darkRadioButton1.TabStop = true;
+            this.darkRadioButton1.Text = "Radiobutton";
+            // 
+            // darkRadioButton2
+            // 
+            this.darkRadioButton2.AutoSize = true;
+            this.darkRadioButton2.Location = new System.Drawing.Point(0, 100);
+            this.darkRadioButton2.Name = "darkRadioButton2";
+            this.darkRadioButton2.Size = new System.Drawing.Size(91, 19);
+            this.darkRadioButton2.TabIndex = 5;
+            this.darkRadioButton2.TabStop = true;
+            this.darkRadioButton2.Text = "Radiobutton";
+            // 
+            // darkRadioButton3
+            // 
+            this.darkRadioButton3.AutoSize = true;
+            this.darkRadioButton3.Enabled = false;
+            this.darkRadioButton3.Location = new System.Drawing.Point(0, 125);
+            this.darkRadioButton3.Name = "darkRadioButton3";
+            this.darkRadioButton3.Size = new System.Drawing.Size(136, 19);
+            this.darkRadioButton3.TabIndex = 6;
+            this.darkRadioButton3.TabStop = true;
+            this.darkRadioButton3.Text = "Disabled radiobutton";
+            // 
             // DockProperties
             // 
             this.AutoScaleDimensions = new System.Drawing.SizeF(7F, 15F);
             this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
-            this.DockArea = DarkDockArea.Right;
+            this.Controls.Add(this.pnlMain);
+            this.DockArea = DarkUI.Config.DarkDockArea.Right;
             this.DockText = "Properties";
             this.Font = new System.Drawing.Font("Segoe UI", 9F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
             this.Icon = global::Example.Icons.properties_16xLG;
             this.Name = "DockProperties";
             this.Size = new System.Drawing.Size(280, 450);
+            this.pnlMain.ResumeLayout(false);
+            this.pnlMain.PerformLayout();
+            this.panel1.ResumeLayout(false);
+            this.panel1.PerformLayout();
             this.ResumeLayout(false);
 
         }
 
         #endregion
+
+        private System.Windows.Forms.Panel pnlMain;
+        private System.Windows.Forms.Panel panel1;
+        private DarkUI.Controls.DarkCheckBox darkCheckBox1;
+        private DarkUI.Controls.DarkCheckBox darkCheckBox2;
+        private DarkUI.Controls.DarkCheckBox darkCheckBox3;
+        private DarkUI.Controls.DarkRadioButton darkRadioButton3;
+        private DarkUI.Controls.DarkRadioButton darkRadioButton2;
+        private DarkUI.Controls.DarkRadioButton darkRadioButton1;
     }
 }
diff --git a/Example/Forms/MainForm.cs b/Example/Forms/MainForm.cs
index b9ece26..7e481db 100644
--- a/Example/Forms/MainForm.cs
+++ b/Example/Forms/MainForm.cs
@@ -56,6 +56,9 @@ namespace Example
             foreach (var toolWindow in _toolWindows)
                 DockPanel.AddContent(toolWindow);
 
+            // Add the history panel to the layer panel group
+            DockPanel.AddContent(_dockHistory, _dockLayers.DockGroup);
+
             // Check window menu items which are contained in the dock panel
             BuildWindowMenu();