3rdpartylibs/fastreports.wpf/FastReport.Forms.WPF/Controls/ToolStripSplitButton.cs

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);
            };
        }
    }
}