// the magic add a new tab page at the end public override void ModifyTabPages(TabControl tabControl) { TabPage page = new TabPage { Tag = tabControl.TabCount + 1, // at end used for undock/dock feature to define the order Text = "Multi Editor" }; _multiEditorControl = new UserControls.MultiEditorControl { Dock = DockStyle.Fill }; page.Controls.Add(_multiEditorControl); tabControl.TabPages.Add(page); }