namespace System.Windows.Forms { public class ToolStripSplitButton : ToolStripDropDownButtonBase { private CustomControls.ToolStripSplitButton button; public event EventHandler ButtonClick; protected virtual void OnButtonClick(EventArgs e) => ButtonClick?.Invoke(this, e); public ToolStripSplitButton() { button = new(); SetButton(button); button.Click += (s, e) => OnButtonClick(EventArgs.Empty); button.SplitButtonClick += (s, e) => { if (!DropDown.Visible) DropDown.Show(this); }; } } }