I need to have all the new forms created based on a custom config that determines how many forms are needed to have the same features (icon and custom menu actions). I get CS1540 error on form.WndProc += (ref Message m) => line.

    private void SetupSystemMenu(Form form)
    {
    // Add your icon to the form (if applicable)
    form.Icon = this.Icon;

    // Hook into the form's HandleCreated event to set up the system menu
    form.HandleCreated += (sender, e) =>
    {
        IntPtr systemMenuHandle = GetSystemMenu(form.Handle, false);

        // Add a separator and then our custom items
        AppendMenu(systemMenuHandle, MF_SEPARATOR, 0, string.Empty);
        AppendMenu(systemMenuHandle, MF_STRING, SYSMENU_CUSTOM_ITEM_ID, "Erase Config");
        AppendMenu(systemMenuHandle, MF_STRING, SYSMENU_PAUSE_TIMER_ID, "Pause Timer");
        AppendMenu(systemMenuHandle, MF_STRING, SYSMENU_REFRESH_NOW_ID, "Refresh Now");
    };

    // Hook into the WndProc of the form to handle menu item clicks
    form.WndProc += (ref Message m) =>
    {
        if (m.Msg == WM_SYSCOMMAND)
        {
            switch (m.WParam.ToInt32())
            {
                case SYSMENU_CUSTOM_ITEM_ID:
                    EraseConfig();
                    break;

                case SYSMENU_PAUSE_TIMER_ID:
                    ToggleTimerPause();
                    break;

                case SYSMENU_REFRESH_NOW_ID:
                    Program.refreshRequested = true;
                    refreshTimer.Stop();
                    form.Close();
                    break;
            }
        }
        form.WndProc(ref m);
    };
}